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Neptune's more varied weather when compared to Uranus is due in part to its higher internal heating. Although Neptune lies over 50% further from the Sun than Uranus, and receives only 40% its amount of sunlight, the two planets' surface temperatures are roughly equal. The upper regions of Neptune's troposphere reach a low temperature of 51.8 K (−221.3 °C). At a depth where the atmospheric pressure equals 1 bar (100 kPa), the temperature is 72.00 K (−201.15 °C). Deeper inside the layers of gas, the temperature rises steadily. As with Uranus, the source of this heating is unknown, but the discrepancy is larger: Uranus only radiates 1.1 times as much energy as it receives from the Sun; whereas Neptune radiates about 2.61 times as much energy as it receives from the Sun. Neptune is the farthest planet from the Sun, yet its internal energy is sufficient to drive the fastest planetary winds seen in the Solar System. Depending on the thermal properties of its interior, the heat left over from Neptune's formation may be sufficient to explain its current heat flow, though it is more difficult to simultaneously explain Uranus's lack of internal heat while preserving the apparent similarity between the two planets.
On 11 July 2011, Neptune completed its first full barycentric orbit since its discovery in 1846, although it did not appear at its exact discovery position in the sky, because Earth was in a different location in its 365.26-day orbit. Because of the motion of the Sun in relation to the barycentre of the Solar System, on 11 July Neptune was also not at its exact discovery position in relation to the Sun; if the more common heliocentric coordinate system is used, the discovery longitude was reached on 12 July 2011.
Neptune's orbit has a profound impact on the region directly beyond it, known as the Kuiper belt. The Kuiper belt is a ring of small icy worlds, similar to the asteroid belt but far larger, extending from Neptune's orbit at 30 AU out to about 55 AU from the Sun. Much in the same way that Jupiter's gravity dominates the asteroid belt, shaping its structure, so Neptune's gravity dominates the Kuiper belt. Over the age of the Solar System, certain regions of the Kuiper belt became destabilised by Neptune's gravity, creating gaps in the Kuiper belt's structure. The region between 40 and 42 AU is an example.
There do exist orbits within these empty regions where objects can survive for the age of the Solar System. These resonances occur when Neptune's orbital period is a precise fraction of that of the object, such as 1:2, or 3:4. If, say, an object orbits the Sun once for every two Neptune orbits, it will only complete half an orbit by the time Neptune returns to its original position. The most heavily populated resonance in the Kuiper belt, with over 200 known objects, is the 2:3 resonance. Objects in this resonance complete 2 orbits for every 3 of Neptune, and are known as plutinos because the largest of the known Kuiper belt objects, Pluto, is among them. Although Pluto crosses Neptune's orbit regularly, the 2:3 resonance ensures they can never collide. The 3:4, 3:5, 4:7 and 2:5 resonances are less populated.
Neptune has a number of known trojan objects occupying both the Sun–Neptune L4 and L5 Lagrangian points—gravitationally stable regions leading and trailing Neptune in its orbit, respectively. Neptune trojans can be viewed as being in a 1:1 resonance with Neptune. Some Neptune trojans are remarkably stable in their orbits, and are likely to have formed alongside Neptune rather than being captured. The first and so far only object identified as associated with Neptune's trailing L5 Lagrangian point is 2008 LC18. Neptune also has a temporary quasi-satellite, (309239) 2007 RW10. The object has been a quasi-satellite of Neptune for about 12,500 years and it will remain in that dynamical state for another 12,500 years.
The formation of the ice giants, Neptune and Uranus, has proven difficult to model precisely. Current models suggest that the matter density in the outer regions of the Solar System was too low to account for the formation of such large bodies from the traditionally accepted method of core accretion, and various hypotheses have been advanced to explain their formation. One is that the ice giants were not formed by core accretion but from instabilities within the original protoplanetary disc and later had their atmospheres blasted away by radiation from a nearby massive OB star.
An alternative concept is that they formed closer to the Sun, where the matter density was higher, and then subsequently migrated to their current orbits after the removal of the gaseous protoplanetary disc. This hypothesis of migration after formation is favoured, due to its ability to better explain the occupancy of the populations of small objects observed in the trans-Neptunian region. The current most widely accepted explanation of the details of this hypothesis is known as the Nice model, which explores the effect of a migrating Neptune and the other giant planets on the structure of the Kuiper belt.
Neptune has 14 known moons. Triton is the largest Neptunian moon, comprising more than 99.5% of the mass in orbit around Neptune,[e] and it is the only one massive enough to be spheroidal. Triton was discovered by William Lassell just 17 days after the discovery of Neptune itself. Unlike all other large planetary moons in the Solar System, Triton has a retrograde orbit, indicating that it was captured rather than forming in place; it was probably once a dwarf planet in the Kuiper belt. It is close enough to Neptune to be locked into a synchronous rotation, and it is slowly spiralling inward because of tidal acceleration. It will eventually be torn apart, in about 3.6 billion years, when it reaches the Roche limit. In 1989, Triton was the coldest object that had yet been measured in the Solar System, with estimated temperatures of 38 K (−235 °C).
From July to September 1989, Voyager 2 discovered six moons of Neptune. Of these, the irregularly shaped Proteus is notable for being as large as a body of its density can be without being pulled into a spherical shape by its own gravity. Although the second-most-massive Neptunian moon, it is only 0.25% the mass of Triton. Neptune's innermost four moons—Naiad, Thalassa, Despina and Galatea—orbit close enough to be within Neptune's rings. The next-farthest out, Larissa, was originally discovered in 1981 when it had occulted a star. This occultation had been attributed to ring arcs, but when Voyager 2 observed Neptune in 1989, Larissa was found to have caused it. Five new irregular moons discovered between 2002 and 2003 were announced in 2004. A new moon and the smallest yet, S/2004 N 1, was found in 2013. Because Neptune was the Roman god of the sea, Neptune's moons have been named after lesser sea gods.
Because of the distance of Neptune from Earth, its angular diameter only ranges from 2.2 to 2.4 arcseconds, the smallest of the Solar System planets. Its small apparent size makes it challenging to study it visually. Most telescopic data was fairly limited until the advent of Hubble Space Telescope (HST) and large ground-based telescopes with adaptive optics (AO). The first scientifically useful observation of Neptune from ground-based telescopes using adaptive optics, was commenced in 1997 from Hawaii. Neptune is currently entering its spring and summer season and has been shown to be heating up, with increased atmospheric activity and brightness as a consequence. Combined with technological advancements, ground-based telescopes with adaptive optics are recording increasingly more detailed images of this Outer Planet. Both the HST and AO telescopes on Earth has made many new discoveries within the Solar System since the mid-1990s, with a large increase in the number of known satellites and moons around the Outer Planets for example. In 2004 and 2005, five new small satellites of Neptune with diameters between 38 and 61 kilometres were discovered.
Voyager 2 is the only spacecraft that has visited Neptune. The spacecraft's closest approach to the planet occurred on 25 August 1989. Because this was the last major planet the spacecraft could visit, it was decided to make a close flyby of the moon Triton, regardless of the consequences to the trajectory, similarly to what was done for Voyager 1's encounter with Saturn and its moon Titan. The images relayed back to Earth from Voyager 2 became the basis of a 1989 PBS all-night program, Neptune All Night.
After the Voyager 2 flyby mission, the next step in scientific exploration of the Neptunian system, is considered to be a Flagship orbital mission. Such a hypothetical mission is envisioned to be possible at in the late 2020s or early 2030s. However, there have been a couple of discussions to launch Neptune missions sooner. In 2003, there was a proposal in NASA's "Vision Missions Studies" for a "Neptune Orbiter with Probes" mission that does Cassini-level science. Another, more recent proposal was for Argo, a flyby spacecraft to be launched in 2019, that would visit Jupiter, Saturn, Neptune, and a Kuiper belt object. The focus would be on Neptune and its largest moon Triton to be investigated around 2029. The proposed New Horizons 2 mission (which was later scrapped) might also have done a close flyby of the Neptunian system.
A railway electrification system supplies electric power to railway trains and trams without an on-board prime mover or local fuel supply. Electrification has many advantages but requires significant capital expenditure. Selection of an electrification system is based on economics of energy supply, maintenance, and capital cost compared to the revenue obtained for freight and passenger traffic. Different systems are used for urban and intercity areas; some electric locomotives can switch to different supply voltages to allow flexibility in operation.
Electric railways use electric locomotives to haul passengers or freight in separate cars or electric multiple units, passenger cars with their own motors. Electricity is typically generated in large and relatively efficient generating stations, transmitted to the railway network and distributed to the trains. Some electric railways have their own dedicated generating stations and transmission lines but most purchase power from an electric utility. The railway usually provides its own distribution lines, switches and transformers.
In comparison to the principal alternative, the diesel engine, electric railways offer substantially better energy efficiency, lower emissions and lower operating costs. Electric locomotives are usually quieter, more powerful, and more responsive and reliable than diesels. They have no local emissions, an important advantage in tunnels and urban areas. Some electric traction systems provide regenerative braking that turns the train's kinetic energy back into electricity and returns it to the supply system to be used by other trains or the general utility grid. While diesel locomotives burn petroleum, electricity is generated from diverse sources including many that do not produce carbon dioxide such as nuclear power and renewable forms including hydroelectric, geothermal, wind and solar.
Disadvantages of electric traction include high capital costs that may be uneconomic on lightly trafficked routes; a relative lack of flexibility since electric trains need electrified tracks or onboard supercapacitors and charging infrastructure at stations; and a vulnerability to power interruptions. Different regions may use different supply voltages and frequencies, complicating through service. The limited clearances available under catenaries may preclude efficient double-stack container service. The lethal voltages on contact wires and third rails are a safety hazard to track workers, passengers and trespassers. Overhead wires are safer than third rails, but they are often considered unsightly.
Railways must operate at variable speeds. Until the mid 1980s this was only practical with the brush-type DC motor, although such DC can be supplied from an AC catenary via on-board electric power conversion. Since such conversion was not well developed in the late 19th century and early 20th century, most early electrified railways used DC and many still do, particularly rapid transit (subways) and trams. Speed was controlled by connecting the traction motors in various series-parallel combinations, by varying the traction motors' fields, and by inserting and removing starting resistances to limit motor current.
Motors have very little room for electrical insulation so they generally have low voltage ratings. Because transformers (prior to the development of power electronics) cannot step down DC voltages, trains were supplied with a relatively low DC voltage that the motors can use directly. The most common DC voltages are listed in the previous section. Third (and fourth) rail systems almost always use voltages below 1 kV for safety reasons while overhead wires usually use higher voltages for efficiency. ("Low" voltage is relative; even 600 V can be instantly lethal when touched.)
There has, however, been interest among railroad operators in returning to DC use at higher voltages than previously used. At the same voltage, DC often has less loss than AC, and for this reason high-voltage direct current is already used on some bulk power transmission lines. DC avoids the electromagnetic radiation inherent with AC, and on a railway this also reduces interference with signalling and communications and mitigates hypothetical EMF risks. DC also avoids the power factor problems of AC. Of particular interest to railroading is that DC can supply constant power with a single ungrounded wire. Constant power with AC requires three-phase transmission with at least two ungrounded wires. Another important consideration is that mains-frequency 3-phase AC must be carefully planned to avoid unbalanced phase loads. Parts of the system are supplied from different phases on the assumption that the total loads of the 3 phases will even out. At the phase break points between regions supplied from different phases, long insulated supply breaks are required to avoid them being shorted by rolling stock using more than one pantograph at a time. A few railroads have tried 3-phase but its substantial complexity has made single-phase standard practice despite the interruption in power flow that occurs twice every cycle. An experimental 6 kV DC railway was built in the Soviet Union.
1,500 V DC is used in the Netherlands, Japan, Republic Of Indonesia, Hong Kong (parts), Republic of Ireland, Australia (parts), India (around the Mumbai area alone, has been converted to 25 kV AC like the rest of India), France (also using 25 kV 50 Hz AC), New Zealand (Wellington) and the United States (Chicago area on the Metra Electric district and the South Shore Line interurban line). In Slovakia, there are two narrow-gauge lines in the High Tatras (one a cog railway). In Portugal, it is used in the Cascais Line and in Denmark on the suburban S-train system.
3 kV DC is used in Belgium, Italy, Spain, Poland, the northern Czech Republic, Slovakia, Slovenia, South Africa, Chile, and former Soviet Union countries (also using 25 kV 50 Hz AC). It was formerly used by the Milwaukee Road from Harlowton, Montana to Seattle-Tacoma, across the Continental Divide and including extensive branch and loop lines in Montana, and by the Delaware, Lackawanna & Western Railroad (now New Jersey Transit, converted to 25 kV AC) in the United States, and the Kolkata suburban railway (Bardhaman Main Line) in India, before it was converted to 25 kV 50 Hz AC.
Most electrification systems use overhead wires, but third rail is an option up to about 1,200 V. Third rail systems exclusively use DC distribution. The use of AC is not feasible because the dimensions of a third rail are physically very large compared with the skin depth that the alternating current penetrates to (0.3 millimetres or 0.012 inches) in a steel rail). This effect makes the resistance per unit length unacceptably high compared with the use of DC. Third rail is more compact than overhead wires and can be used in smaller-diameter tunnels, an important factor for subway systems.
DC systems (especially third-rail systems) are limited to relatively low voltages and this can limit the size and speed of trains and cannot use low-level platform and also limit the amount of air-conditioning that the trains can provide. This may be a factor favouring overhead wires and high-voltage AC, even for urban usage. In practice, the top speed of trains on third-rail systems is limited to 100 mph (160 km/h) because above that speed reliable contact between the shoe and the rail cannot be maintained.
Some street trams (streetcars) used conduit third-rail current collection. The third rail was below street level. The tram picked up the current through a plough (U.S. "plow") accessed through a narrow slot in the road. In the United States, much (though not all) of the former streetcar system in Washington, D.C. (discontinued in 1962) was operated in this manner to avoid the unsightly wires and poles associated with electric traction. The same was true with Manhattan's former streetcar system. The evidence of this mode of running can still be seen on the track down the slope on the northern access to the abandoned Kingsway Tramway Subway in central London, United Kingdom, where the slot between the running rails is clearly visible, and on P and Q Streets west of Wisconsin Avenue in the Georgetown neighborhood of Washington DC, where the abandoned tracks have not been paved over. The slot can easily be confused with the similar looking slot for cable trams/cars (in some cases, the conduit slot was originally a cable slot). The disadvantage of conduit collection included much higher initial installation costs, higher maintenance costs, and problems with leaves and snow getting in the slot. For this reason, in Washington, D.C. cars on some lines converted to overhead wire on leaving the city center, a worker in a "plough pit" disconnecting the plough while another raised the trolley pole (hitherto hooked down to the roof) to the overhead wire. In New York City for the same reasons of cost and operating efficiency outside of Manhattan overhead wire was used. A similar system of changeover from conduit to overhead wire was also used on the London tramways, notably on the southern side; a typical changeover point was at Norwood, where the conduit snaked sideways from between the running rails, to provide a park for detached shoes or ploughs.
A new approach to avoiding overhead wires is taken by the "second generation" tram/streetcar system in Bordeaux, France (entry into service of the first line in December 2003; original system discontinued in 1958) with its APS (alimentation par sol – ground current feed). This involves a third rail which is flush with the surface like the tops of the running rails. The circuit is divided into segments with each segment energized in turn by sensors from the car as it passes over it, the remainder of the third rail remaining "dead". Since each energized segment is completely covered by the lengthy articulated cars, and goes dead before being "uncovered" by the passage of the vehicle, there is no danger to pedestrians. This system has also been adopted in some sections of the new tram systems in Reims, France (opened 2011) and Angers, France (also opened 2011). Proposals are in place for a number of other new services including Dubai, UAE; Barcelona, Spain; Florence, Italy; Marseille, France; Gold Coast, Australia; Washington, D.C., U.S.A.; Brasília, Brazil and Tours, France.
The London Underground in England is one of the few networks that uses a four-rail system. The additional rail carries the electrical return that, on third rail and overhead networks, is provided by the running rails. On the London Underground, a top-contact third rail is beside the track, energized at +420v DC, and a top-contact fourth rail is located centrally between the running rails at −210v DC, which combine to provide a traction voltage of 630v DC. London Underground is now upgrading its fourth rail system to 750v DC with a positive conductor rail energised to +500v DC and a negative conductor rail energised to -250v DC. However, many older sections in tunnels are still energised to 630v DC. The same system was used for Milan's earliest underground line, Milan Metro's line 1, whose more recent lines use an overhead catenary or a third rail.
The key advantage of the four-rail system is that neither running rail carries any current. This scheme was introduced because of the problems of return currents, intended to be carried by the earthed (grounded) running rail, flowing through the iron tunnel linings instead. This can cause electrolytic damage and even arcing if the tunnel segments are not electrically bonded together. The problem was exacerbated because the return current also had a tendency to flow through nearby iron pipes forming the water and gas mains. Some of these, particularly Victorian mains that predated London's underground railways, were not constructed to carry currents and had no adequate electrical bonding between pipe segments. The four-rail system solves the problem. Although the supply has an artificially created earth point, this connection is derived by using resistors which ensures that stray earth currents are kept to manageable levels. Power-only rails can be mounted on strongly insulating ceramic chairs to minimise current leak, but this is not possible for running rails which have to be seated on stronger metal chairs to carry the weight of trains. However, elastomeric rubber pads placed between the rails and chairs can now solve part of the problem by insulating the running rails from the current return should there be a leakage through the running rails.
On tracks that London Underground share with National Rail third-rail stock (the Bakerloo and District lines both have such sections), the centre rail is connected to the running rails, allowing both types of train to operate, at a compromise voltage of 660 V. Underground trains pass from one section to the other at speed; lineside electrical connections and resistances separate the two types of supply. These routes were originally solely electrified on the four-rail system by the LNWR before National Rail trains were rewired to their standard three-rail system to simplify rolling stock use.
A few lines of the Paris Métro in France operate on a four-rail power scheme because they run on rubber tyres which run on a pair of narrow roadways made of steel and, in some places, concrete. Since the tyres do not conduct the return current, the two guide rails provided outside the running 'roadways' double up as conductor rails, so at least electrically it is a four-rail scheme. One of the guide rails is bonded to the return conventional running rails situated inside the roadway so a single polarity supply is required. The trains are designed to operate from either polarity of supply, because some lines use reversing loops at one end, causing the train to be reversed during every complete journey. The loop was originally provided to save the original steam locomotives having to 'run around' the rest of the train saving much time. Today, the driver does not have to change ends at termini provided with such a loop, but the time saving is not so significant as it takes almost as long to drive round the loop as it does to change ends. Many of the original loops have been lost as lines were extended.
An early advantage of AC is that the power-wasting resistors used in DC locomotives for speed control were not needed in an AC locomotive: multiple taps on the transformer can supply a range of voltages. Separate low-voltage transformer windings supply lighting and the motors driving auxiliary machinery. More recently, the development of very high power semiconductors has caused the classic "universal" AC/DC motor to be largely replaced with the three-phase induction motor fed by a variable frequency drive, a special inverter that varies both frequency and voltage to control motor speed. These drives can run equally well on DC or AC of any frequency, and many modern electric locomotives are designed to handle different supply voltages and frequencies to simplify cross-border operation.
DC commutating electric motors, if fitted with laminated pole pieces, become universal motors because they can also operate on AC; reversing the current in both stator and rotor does not reverse the motor. But the now-standard AC distribution frequencies of 50 and 60 Hz caused difficulties with inductive reactance and eddy current losses. Many railways chose low AC frequencies to overcome these problems. They must be converted from utility power by motor-generators or static inverters at the feeding substations or generated at dedicated traction powerstations.
High-voltage AC overhead systems are not only for standard gauge national networks. The meter gauge Rhaetian Railway (RhB) and the neighbouring Matterhorn Gotthard Bahn (MGB) operate on 11 kV at 16.7 Hz frequency. Practice has proven that both Swiss and German 15 kV trains can operate under these lower voltages. The RhB started trials of the 11 kV system in 1913 on the Engadin line (St. Moritz-Scuol/Tarasp). The MGB constituents Furka-Oberalp-Bahn (FO) and Brig-Visp-Zermatt Bahn (BVZ) introduced their electric services in 1941 and 1929 respectively, adopting the already proven RhB system.
In the United States, 25 Hz, a once-common industrial power frequency is used on Amtrak's 25 Hz traction power system at 12 kV on the Northeast Corridor between Washington, D.C. and New York City and on the Keystone Corridor between Harrisburg, Pennsylvania and Philadelphia. SEPTA's 25 Hz traction power system uses the same 12 kV voltage on the catenary in Northeast Philadelphia. This allows for the trains to operate on both the Amtrak and SEPTA power systems. Apart from having an identical catenary voltage, the power distribution systems of Amtrak and SEPTA are very different. The Amtrak power distribution system has a 138 kV transmission network that provides power to substations which then transform the voltage to 12 kV to feed the catenary system. The SEPTA power distribution system uses a 2:1 ratio autotransformer system, with the catenary fed at 12 kV and a return feeder wire fed at 24 kV. The New York, New Haven and Hartford Railroad used an 11 kV system between New York City and New Haven, Connecticut which was converted to 12.5 kV 60 Hz in 1987.
In the UK, the London, Brighton and South Coast Railway pioneered overhead electrification of its suburban lines in London, London Bridge to Victoria being opened to traffic on 1 December 1909. Victoria to Crystal Palace via Balham and West Norwood opened in May 1911. Peckham Rye to West Norwood opened in June 1912. Further extensions were not made owing to the First World War. Two lines opened in 1925 under the Southern Railway serving Coulsdon North and Sutton railway station. The lines were electrified at 6.7 kV 25 Hz. It was announced in 1926 that all lines were to be converted to DC third rail and the last overhead electric service ran in September 1929.
Three-phase AC railway electrification was used in Italy, Switzerland and the United States in the early twentieth century. Italy was the major user, for lines in the mountainous regions of northern Italy from 1901 until 1976. The first lines were the Burgdorf-Thun line in Switzerland (1899), and the lines of the Ferrovia Alta Valtellina from Colico to Chiavenna and Tirano in Italy, which were electrified in 1901 and 1902. Other lines where the three-phase system were used were the Simplon Tunnel in Switzerland from 1906 to 1930, and the Cascade Tunnel of the Great Northern Railway in the United States from 1909 to 1927.
The first attempts to use standard-frequency single-phase AC were made in Hungary as far back as 1923, by the Hungarian Kálmán Kandó on the line between Budapest-Nyugati and Alag, using 16 kV at 50 Hz. The locomotives carried a four-pole rotating phase converter feeding a single traction motor of the polyphase induction type at 600 to 1,100 V. The number of poles on the 2,500 hp motor could be changed using slip rings to run at one of four synchronous speeds. The tests were a success so, from 1932 until the 1960s, trains on the Budapest-Hegyeshalom line (towards Vienna) regularly used the same system. A few decades after the Second World War, the 16 kV was changed to the Russian and later French 25 kV system.
To prevent the risk of out-of-phase supplies mixing, sections of line fed from different feeder stations must be kept strictly isolated. This is achieved by Neutral Sections (also known as Phase Breaks), usually provided at feeder stations and midway between them although, typically, only half are in use at any time, the others being provided to allow a feeder station to be shut down and power provided from adjacent feeder stations. Neutral Sections usually consist of an earthed section of wire which is separated from the live wires on either side by insulating material, typically ceramic beads, designed so that the pantograph will smoothly run from one section to the other. The earthed section prevents an arc being drawn from one live section to the other, as the voltage difference may be higher than the normal system voltage if the live sections are on different phases and the protective circuit breakers may not be able to safely interrupt the considerable current that would flow. To prevent the risk of an arc being drawn across from one section of wire to earth, when passing through the neutral section, the train must be coasting and the circuit breakers must be open. In many cases, this is done manually by the drivers. To help them, a warning board is provided just before both the neutral section and an advance warning some distance before. A further board is then provided after the neutral section to tell drivers to re-close the circuit breaker, although drivers must not do this until the rear pantograph has passed this board. In the UK, a system known as Automatic Power Control (APC) automatically opens and closes the circuit breaker, this being achieved by using sets of permanent magnets alongside the track communicating with a detector on the train. The only action needed by the driver is to shut off power and coast and therefore warning boards are still provided at and on the approach to neutral sections.
Modern electrification systems take AC energy from a power grid which is delivered to a locomotive and converted to a DC voltage to be used by traction motors. These motors may either be DC motors which directly use the DC or they may be 3-phase AC motors which require further conversion of the DC to 3-phase AC (using power electronics). Thus both systems are faced with the same task: converting and transporting high-voltage AC from the power grid to low-voltage DC in the locomotive. Where should this conversion take place and at what voltage and current (AC or DC) should the power flow to the locomotive? And how does all this relate to energy-efficiency? Both the transmission and conversion of electric energy involve losses: ohmic losses in wires and power electronics, magnetic field losses in transformers and smoothing reactors (inductors). Power conversion for a DC system takes place mainly in a railway substation where large, heavy, and more efficient hardware can be used as compared to an AC system where conversion takes place aboard the locomotive where space is limited and losses are significantly higher. Also, the energy used to blow air to cool transformers, power electronics (including rectifiers), and other conversion hardware must be accounted for.
In the Soviet Union, in the 1970s, a comparison was made between systems electrified at 3 kV DC and 25 kV AC (50 Hz). The results showed that percentage losses in the overhead wires (catenary and contact wires) was over 3 times greater for 3 kV DC than for 25 kV AC. But when the conversion losses were all taken into account and added to overhead wire losses (including cooling blower energy) the 25 kV AC lost a somewhat higher percent of energy than for 3 kV DC. Thus in spite of the much higher losses in the catenary, the 3 kV DC was a little more energy efficient than AC in providing energy from the USSR power grid to the terminals of the traction motors (all DC at that time). While both systems use energy in converting higher voltage AC from the USSR's power grid to lower voltage DC, the conversions for the DC system all took place (at higher efficiency) in the railway substation, while most of the conversion for the AC system took place inside the locomotive (at lower efficiency). Consider also that it takes energy to constantly move this mobile conversion hardware over the rails while the stationary hardware in the railway substation doesn't incur this energy cost. For more details see: Wiki: Soviet Union DC vs. AC.
Newly electrified lines often show a "sparks effect", whereby electrification in passenger rail systems leads to significant jumps in patronage / revenue. The reasons may include electric trains being seen as more modern and attractive to ride, faster and smoother service, and the fact that electrification often goes hand in hand with a general infrastructure and rolling stock overhaul / replacement, which leads to better service quality (in a way that theoretically could also be achieved by doing similar upgrades yet without electrification). Whatever the causes of the sparks effect, it is well established for numerous routes that have electrified over decades.
Network effects are a large factor with electrification. When converting lines to electric, the connections with other lines must be considered. Some electrifications have subsequently been removed because of the through traffic to non-electrified lines. If through traffic is to have any benefit, time consuming engine switches must occur to make such connections or expensive dual mode engines must be used. This is mostly an issue for long distance trips, but many lines come to be dominated by through traffic from long-haul freight trains (usually running coal, ore, or containers to or from ports). In theory, these trains could enjoy dramatic savings through electrification, but it can be too costly to extend electrification to isolated areas, and unless an entire network is electrified, companies often find that they need to continue use of diesel trains even if sections are electrified. The increasing demand for container traffic which is more efficient when utilizing the double-stack car also has network effect issues with existing electrifications due to insufficient clearance of overhead electrical lines for these trains, but electrification can be built or modified to have sufficient clearance, at additional cost.
Additionally, there are issues of connections between different electrical services, particularly connecting intercity lines with sections electrified for commuter traffic, but also between commuter lines built to different standards. This can cause electrification of certain connections to be very expensive simply because of the implications on the sections it is connecting. Many lines have come to be overlaid with multiple electrification standards for different trains to avoid having to replace the existing rolling stock on those lines. Obviously, this requires that the economics of a particular connection must be more compelling and this has prevented complete electrification of many lines. In a few cases, there are diesel trains running along completely electrified routes and this can be due to incompatibility of electrification standards along the route.
Central station electricity can often be generated with higher efficiency than a mobile engine/generator. While the efficiency of power plant generation and diesel locomotive generation are roughly the same in the nominal regime, diesel motors decrease in efficiency in non-nominal regimes at low power while if an electric power plant needs to generate less power it will shut down its least efficient generators, thereby increasing efficiency. The electric train can save energy (as compared to diesel) by regenerative braking and by not needing to consume energy by idling as diesel locomotives do when stopped or coasting. However, electric rolling stock may run cooling blowers when stopped or coasting, thus consuming energy.
Energy sources unsuitable for mobile power plants, such as nuclear power, renewable hydroelectricity, or wind power can be used. According to widely accepted global energy reserve statistics, the reserves of liquid fuel are much less than gas and coal (at 42, 167 and 416 years respectively). Most countries with large rail networks do not have significant oil reserves and those that did, like the United States and Britain, have exhausted much of their reserves and have suffered declining oil output for decades. Therefore, there is also a strong economic incentive to substitute other fuels for oil. Rail electrification is often considered an important route towards consumption pattern reform. However, there are no reliable, peer-reviewed studies available to assist in rational public debate on this critical issue, although there are untranslated Soviet studies from the 1980s.
In the former Soviet Union, electric traction eventually became somewhat more energy-efficient than diesel. Partly due to inefficient generation of electricity in the USSR (only 20.8% thermal efficiency in 1950 vs. 36.2% in 1975), in 1950 diesel traction was about twice as energy efficient as electric traction (in terms of net tonne-km of freight per kg of fuel). But as efficiency of electricity generation (and thus of electric traction) improved, by about 1965 electric railways became more efficient than diesel. After the mid 1970s electrics used about 25% less fuel per ton-km. However diesels were mainly used on single track lines with a fair amount of traffic so that the lower fuel consumption of electrics may be in part due to better operating conditions on electrified lines (such as double tracking) rather than inherent energy efficiency. Nevertheless, the cost of diesel fuel was about 1.5 times more (per unit of heat energy content) than that of the fuel used in electric power plants (that generated electricity), thus making electric railways even more energy-cost effective.
Besides increased efficiency of power plants, there was an increase in efficiency (between 1950 and 1973) of the railway utilization of this electricity with energy-intensity dropping from 218 to 124 kwh/10,000 gross tonne-km (of both passenger and freight trains) or a 43% drop. Since energy-intensity is the inverse of energy-efficiency it drops as efficiency goes up. But most of this 43% decrease in energy-intensity also benefited diesel traction. The conversion of wheel bearings from plain to roller, increase of train weight, converting single track lines to double track (or partially double track), and the elimination of obsolete 2-axle freight cars increased the energy-efficiency of all types of traction: electric, diesel, and steam. However, there remained a 12–15% reduction of energy-intensity that only benefited electric traction (and not diesel). This was due to improvements in locomotives, more widespread use of regenerative braking (which in 1989 recycled 2.65% of the electric energy used for traction,) remote control of substations, better handling of the locomotive by the locomotive crew, and improvements in automation. Thus the overall efficiency of electric traction as compared to diesel more than doubled between 1950 and the mid-1970s in the Soviet Union. But after 1974 (thru 1980) there was no improvement in energy-intensity (wh/tonne-km) in part due to increasing speeds of passenger and freight trains.
The Spanish language is the second most spoken language in the United States. There are 45 million Hispanophones who speak Spanish as a first or second language in the United States, as well as six million Spanish language students. Together, this makes the United States of America the second largest Hispanophone country in the world after Mexico, and with the United States having more Spanish-speakers than Colombia and Spain (but fewer first language speakers). Spanish is the Romance language and the Indo-European language with the largest number of native speakers in the world. Roughly half of all American Spanish-speakers also speak English "very well," based on their self-assessment in the U.S. Census.
The Spanish language has been present in what is now the United States since the 16th and 17th centuries, with the arrival of Spanish colonization in North America that would later become the states of Florida, Texas, Colorado, New Mexico, Arizona, Nevada, Utah, and California. The Spanish explorers explored areas of 42 future U.S. states leaving behind a varying range of Hispanic legacy in the North American continent. Additionally, western regions of the Louisiana Territory were under Spanish rule between 1763 to 1800, after the French and Indian War, further extending the Spanish influence throughout modern-day United States of America.
Spanish was the language spoken by the first permanent European settlers in North America. Spanish arrived in the territory of the modern United States with Ponce de León in 1513. In 1565, the Spaniards, by way of Juan Ponce de León, founded St. Augustine, Florida, and as of the early 1800s, it became the oldest continuously occupied European settlement in the continental United States. The oldest city in all of the U.S. territory, as of 1898, is San Juan, capital of Puerto Rico, where Juan Ponce De León was its first governor
In 1821, after Mexico's War of Independence from Spain, Texas was part of the United Mexican States as the state of Coahuila y Tejas. A large influx of Americans soon followed, originally with the approval of Mexico's president. In 1836, the now largely "American" Texans, fought a war of independence from the central government of Mexico and established the Republic of Texas. In 1846, the Republic dissolved when Texas entered the United States of America as a state. Per the 1850 U.S. census, fewer than 16,000 Texans were of Mexican descent, and nearly all were Spanish-speaking people (both Mexicans and non-Spanish European settlers who include German Texan) who were outnumbered (six-to-one) by English-speaking settlers (both Americans and other immigrant Europeans).[citation needed]
After the Mexican War of Independence from Spain also, California, Nevada, Arizona, Utah, western Colorado and southwestern Wyoming became part of the Mexican territory of Alta California and most of New Mexico, western Texas, southern Colorado, southwestern Kansas, and Oklahoma panhandle were part of the territory of Santa Fe de Nuevo México. The geographical isolation and unique political history of this territory led to New Mexican Spanish differing notably from both Spanish spoken in other parts of the United States of America and Spanish spoken in the present-day United Mexican States.
Through the force of sheer numbers, the English-speaking American settlers entering the Southwest established their language, culture, and law as dominant, to the extent it fully displaced Spanish in the public sphere; this is why the United States never developed bilingualism as Canada did. For example, the California constitutional convention of 1849 had eight Californio participants; the resulting state constitution was produced in English and Spanish, and it contained a clause requiring all published laws and regulations to be published in both languages. The constitutional convention of 1872 had no Spanish-speaking participants; the convention's English-speaking participants felt that the state's remaining minority of Spanish-speakers should simply learn English; and the convention ultimately voted 46-39 to revise the earlier clause so that all official proceedings would henceforth be published only in English.
For decades, the U.S. federal government strenuously tried to force Puerto Ricans to adopt English, to the extent of making them use English as the primary language of instruction in their high schools. It was completely unsuccessful, and retreated from that policy in 1948. Puerto Rico was able to maintain its Spanish language, culture, and identity because the relatively small, densely populated island was already home to nearly a million people at the time of the U.S. takeover, all of those spoke Spanish, and the territory was never hit with a massive influx of millions of English speakers like the vast territory acquired from Mexico 50 years earlier.
At over 5 million, Puerto Ricans are easily the 2nd largest Hispanic group. Of all major Hispanic groups, Puerto Ricans are the least likely to be proficient in Spanish, but millions of Puerto Rican Americans living in the U.S. mainland nonetheless are fluent in Spanish. Puerto Ricans are natural-born U.S. citizens, and many Puerto Ricans have migrated to New York City, Orlando, Philadelphia, and other areas of the Eastern United States, increasing the Spanish-speaking populations and in some areas being the majority of the Hispanophone population, especially in Central Florida. In Hawaii, where Puerto Rican farm laborers and Mexican ranchers have settled since the late 19th century, 7.0 per cent of the islands' people are either Hispanic or Hispanophone or both.
Immigration to the United States of Spanish-speaking Cubans began because of Cuba's political instability upon achieving independence. The deposition of Fulgencio Batista's dictatorship and the ascension of Fidel Castro's government in 1959 increased Cuban immigration to the United States, hence there are some one million Cubans in the United States, most settled in southern and central Florida, while other Cubans live in the Northeastern United States; most are fluent in Spanish. In the city of Miami today Spanish is the first language mostly due to Cuban immigration.
Likewise the migration of Spanish-speaking Nicaraguans also began as a result of political instability during the end of the 1970s and the 1980s. The uprising of the Sandinista revolution which toppled the Somoza dictatorship in 1979 caused many Nicaraguans to migrate particularly from those opposing the Sandinistas. Throughout the 1980s with the United States supported Contra War (or Contra-revolutionary war) which continued up until 1988, and the economic collapse of the country many more Nicaraguans migrated to the United States amongst other countries. The states of the United States where most Nicaraguans migrated to include Florida, California and Texas.
The exodus of Salvadorans was a result of both economic and political problems. The largest immigration wave occurred as a result of the Salvadoran Civil War in the 1980s, in which 20–30% of El Salvador's population emigrated. About 50%, or up to 500,000 of those who escaped headed to the United States, which was already home to over 10,000 Salvadorans, making Salvadorans Americans the fourth-largest Hispanic and Latino American group, after the Mexican-American majority, stateside Puerto Ricans, and Cubans.
As civil wars engulfed several Central American countries in the 1980s, hundreds of thousands of Salvadorans fled their country and came to the United States. Between 1980 and 1990, the Salvadoran immigrant population in the United States increased nearly fivefold from 94,000 to 465,000. The number of Salvadoran immigrants in the United States continued to grow in the 1990s and 2000s as a result of family reunification and new arrivals fleeing a series of natural disasters that hit El Salvador, including earthquakes and hurricanes. By 2008, there were about 1.1 million Salvadoran immigrants in the United States.
Until the 20th century, there was no clear record of the number of Venezuelans who emigrated to the United States. Between the 18th and early 19th centuries, there were many European immigrants who went to Venezuela, only to later migrate to the United States along with their children and grandchildren who born and/or grew up in Venezuela speaking Spanish. From 1910 to 1930, it is estimated that over 4,000 South Americans each year emigrated to the United States; however, there are few specific figures indicating these statistics. Many Venezuelans settled in the United States with hopes of receiving a better education, only to remain in there following graduation. They are frequently joined by relatives. However, since the early 1980s, the reasons for Venezuelan emigration have changed to include hopes of earning a higher salary and due to the economic fluctuations in Venezuela which also promoted an important migration of Venezuelan professionals to the US.
In the 2000s, more Venezuelans opposing the economic and political policies of president Hugo Chávez migrated to the United States (mostly to Florida, but New York City and Houston are other destinations). The largest concentration of Venezuelans in the United States is in South Florida, especially the suburbs of Doral and Weston. Other main states with Venezuelan American populations are, according to the 1990 census, New York, California, Texas (adding their existing Hispanic populations), New Jersey, Massachusetts and Maryland. Some of the urban areas with a high Venezuelan community include Miami, New York City, Los Angeles, and Washington, D.C.
Although the United States has no de jure official language, English is the dominant language of business, education, government, religion, media, culture, civil society, and the public sphere. Virtually all state and federal government agencies and large corporations use English as their internal working language, especially at the management level. Some states, such as New Mexico, provide bilingual legislated notices and official documents, in Spanish and English, and other commonly used languages. By 2015, there was a trend that most Americans and American residents who are of Hispanic descent speak only English in the home.
The state (like its southwestern neighbors) has had close linguistic and cultural ties with Mexico. The state outside the Gadsden Purchase of 1853 was part of the New Mexico Territory until 1863, when the western half was made into the Arizona Territory. The area of the former Gadsden Purchase contained a majority of Spanish-speakers until the 1940s, although the Tucson area had a higher ratio of anglophones (including Mexican Americans who were fluent in English); the continuous arrival of Mexican settlers increases the number of Spanish-speakers.
New Mexico is commonly thought to have Spanish as an official language alongside English because of its wide usage and legal promotion of Spanish in the state; however, the state has no official language. New Mexico's laws are promulgated bilingually in Spanish and English. Although English is the state government's paper working language, government business is often conducted in Spanish, particularly at the local level. Spanish has been spoken in the New Mexico-Colorado border and the contemporary U.S.–Mexico border since the 16th century.[citation needed]
Because of its relative isolation from other Spanish-speaking areas over most of its 400-year existence, New Mexico Spanish, and in particular the Spanish of northern New Mexico and Colorado has retained many elements of 16th- and 17th-century Spanish and has developed its own vocabulary. In addition, it contains many words from Nahuatl, the language spoken by the ancient Aztecs of Mexico. New Mexican Spanish also contains loan words from the Pueblo languages of the upper Rio Grande Valley, Mexican-Spanish words (mexicanismos), and borrowings from English. Grammatical changes include the loss of the second person verb form, changes in verb endings, particularly in the preterite, and partial merging of the second and third conjugations.
In Texas, English is the state's de facto official language (though it lacks de jure status) and is used in government. However, the continual influx of Spanish-speaking immigrants increased the import of Spanish in Texas. Texas's counties bordering Mexico are mostly Hispanic, and consequently, Spanish is commonly spoken in the region. The Government of Texas, through Section 2054.116 of the Government Code, mandates that state agencies provide information on their websites in Spanish to assist residents who have limited English proficiency.
Spanish is currently the most widely taught non-English language in American secondary schools and of higher education. More than 1.4 million university students were enrolled in language courses in autumn of 2002 and Spanish is the most widely taught language in American colleges and universities with 53 percent of the total number of people enrolled, followed by French (14.4%), German (7.1%), Italian (4.5%), American Sign language (4.3%), Japanese (3.7%), and Chinese (2.4%) although the totals remain relatively small in relation to the total U.S population.
The State of the Union Addresses and other presidential speeches are translated to Spanish, following the precedent set by the Bill Clinton administration. Official Spanish translations are available at WhiteHouse.gov. Moreover, non-Hispanic American origin politicians fluent in Spanish-speak in Spanish to Hispanic majority constituencies. There are 500 Spanish newspapers, 152 magazines, and 205 publishers in the United States; magazine and local television advertising expenditures for the Hispanic market have increased much from 1999 to 2003, with growth of 58 percent and 43 percent, respectively.
Calvin Veltman undertook, for the National Center for Education Statistics and for the Hispanic Policy Development Project, the most complete study of English language adoption by Hispanophone immigrants. Mr Veltman's language shift studies document high bilingualism rates and subsequent adoption of English as the preferred language of Hispanics, particularly by the young and the native-born. The complete set of these studies' demographic projections postulates the near-complete assimilation of a given Hispanophone immigrant cohort within two generations. Although his study based itself upon a large 1976 sample from the Bureau of the Census (which has not been repeated), data from the 1990 Census tend to confirm the great Anglicization of the US Hispanic American origin population.
After the incorporation of these states to the United States in the first half of the 19th century, the Spanish language was later reinforced in the country by the acquisition of Puerto Rico in 1898. Later waves of emigration from Mexico, Cuba, El Salvador and elsewhere in Hispanic America to the United States beginning in the second half of the 19th century to the present-day have strengthened the role of the Spanish language in the country. Today, Hispanics are one of the fastest growing demographics in the United States, thus increasing the use and importance of American Spanish in the United States.
Charleston is the oldest and second-largest city in the U.S. state of South Carolina, the county seat of Charleston County, and the principal city in the Charleston–North Charleston–Summerville Metropolitan Statistical Area. The city lies just south of the geographical midpoint of South Carolina's coastline and is located on Charleston Harbor, an inlet of the Atlantic Ocean formed by the confluence of the Ashley and Cooper Rivers, or, as is locally expressed, "where the Cooper and Ashley Rivers come together to form the Atlantic Ocean."
Founded in 1670 as Charles Town in honor of King Charles II of England, Charleston adopted its present name in 1783. It moved to its present location on Oyster Point in 1680 from a location on the west bank of the Ashley River known as Albemarle Point. By 1690, Charles Town was the fifth-largest city in North America, and it remained among the 10 largest cities in the United States through the 1840 census. With a 2010 census population of 120,083 (and a 2014 estimate of 130,113), current trends put Charleston as the fastest-growing municipality in South Carolina. The population of the Charleston metropolitan area, comprising Berkeley, Charleston, and Dorchester Counties, was counted by the 2014 estimate at 727,689 – the third-largest in the state – and the 78th-largest metropolitan statistical area in the United States.
According to the United States Census Bureau, the city has a total area of 127.5 square miles (330.2 km2), of which 109.0 square miles (282.2 km2) is land and 18.5 square miles (47.9 km2) is covered by water. The old city is located on a peninsula at the point where, as Charlestonians say, "The Ashley and the Cooper Rivers come together to form the Atlantic Ocean." The entire peninsula is very low, some is landfill material, and as such, frequently floods during heavy rains, storm surges, and unusually high tides. The city limits have expanded across the Ashley River from the peninsula, encompassing the majority of West Ashley as well as James Island and some of Johns Island. The city limits also have expanded across the Cooper River, encompassing Daniel Island and the Cainhoy area. North Charleston blocks any expansion up the peninsula, and Mount Pleasant occupies the land directly east of the Cooper River.
Charleston has a humid subtropical climate (Köppen climate classification Cfa), with mild winters, hot, humid summers, and significant rainfall all year long. Summer is the wettest season; almost half of the annual rainfall occurs from June to September in the form of thundershowers. Fall remains relatively warm through November. Winter is short and mild, and is characterized by occasional rain. Measurable snow (≥0.1 in or 0.25 cm) only occurs several times per decade at the most, with the last such event occurring December 26, 2010. However, 6.0 in (15 cm) fell at the airport on December 23, 1989, the largest single-day fall on record, contributing to a single-storm and seasonal record of 8.0 in (20 cm) snowfall.
The highest temperature recorded within city limits was 104 °F (40 °C), on June 2, 1985, and June 24, 1944, and the lowest was 7 °F (−14 °C) on February 14, 1899, although at the airport, where official records are kept, the historical range is 105 °F (41 °C) on August 1, 1999 down to 6 °F (−14 °C) on January 21, 1985. Hurricanes are a major threat to the area during the summer and early fall, with several severe hurricanes hitting the area – most notably Hurricane Hugo on September 21, 1989 (a category 4 storm). Dewpoint in the summer ranges from 67.8 to 71.4 °F (20 to 22 °C).
The Charleston-North Charleston-Summerville Metropolitan Statistical Area consists of three counties: Charleston, Berkeley, and Dorchester. As of the 2013 U.S. Census, the metropolitan statistical area had a total population of 712,239 people. North Charleston is the second-largest city in the Charleston-North Charleston-Summerville Metropolitan Statistical Area and ranks as the third-largest city in the state; Mount Pleasant and Summerville are the next-largest cities. These cities combined with other incorporated and unincorporated areas along with the city of Charleston form the Charleston-North Charleston Urban Area with a population of 548,404 as of 2010. The metropolitan statistical area also includes a separate and much smaller urban area within Berkeley County, Moncks Corner (with a 2000 population of 9,123).
The traditional parish system persisted until the Reconstruction Era, when counties were imposed.[citation needed] Nevertheless, traditional parishes still exist in various capacities, mainly as public service districts. When the city of Charleston was formed, it was defined by the limits of the Parish of St. Philip and St. Michael, now also includes parts of St. James' Parish, St. George's Parish, St. Andrew's Parish, and St. John's Parish, although the last two are mostly still incorporated rural parishes.
After Charles II of England (1630–1685) was restored to the English throne in 1660 following Oliver Cromwell's Protectorate, he granted the chartered Province of Carolina to eight of his loyal friends, known as the Lords Proprietors, on March 24, 1663. It took seven years before the group arranged for settlement expeditions. The first of these founded Charles Town, in 1670. Governance, settlement, and development were to follow a visionary plan known as the Grand Model prepared for the Lords Proprietors by John Locke.
The community was established by several shiploads of settlers from Bermuda (which lies due east of South Carolina, although at 1,030 km or 640 mi, it is closest to Cape Hatteras, North Carolina), under the leadership of governor William Sayle, on the west bank of the Ashley River, a few miles northwest of the present-day city center. It was soon predicted by the Earl of Shaftesbury, one of the Lords Proprietors, to become a "great port towne", a destiny the city quickly fulfilled. In 1680, the settlement was moved east of the Ashley River to the peninsula between the Ashley and Cooper Rivers. Not only was this location more defensible, but it also offered access to a fine natural harbor.
The first settlers primarily came from England, its Caribbean colony of Barbados, and its Atlantic colony of Bermuda. Among these were free people of color, born in the West Indies of alliances and marriages between Africans and Englanders, when color lines were looser among the working class in the early colonial years, and some wealthy whites took black consorts or concubines. Charles Town attracted a mixture of ethnic and religious groups. French, Scottish, Irish, and Germans migrated to the developing seacoast town, representing numerous Protestant denominations. Because of the battles between English "royalty" and the Roman Catholic Church, practicing Catholics were not allowed to settle in South Carolina until after the American Revolution. Jews were allowed, and Sephardic Jews migrated to the city in such numbers that by the beginning of the 19th century, the city was home to the largest and wealthiest Jewish community in North America—a status it held until about 1830.
The early settlement was often subject to attack from sea and land, including periodic assaults from Spain and France (both of whom contested England's claims to the region), and pirates. These were combined with raids by Native Americans, who tried to protect themselves from so-called European "settlers," who in turn wanted to expand the settlement. The heart of the city was fortified according to a 1704 plan by Governor Johnson. Except those fronting Cooper River, the walls were largely removed during the 1720s.
Africans were brought to Charles Town on the Middle Passage, first as "servants", then as slaves. Ethnic groups transported here included especially Wolof, Yoruba, Fulani, Igbo, Malinke, and other people of the Windward Coast. An estimated 40% of the total 400,000 Africans transported and sold as slaves into North America are estimated to have landed at Sullivan's Island, just off the port of Charles Town; it is described as a "hellish Ellis Island of sorts .... Today nothing commemorates that ugly fact but a simple bench, established by the author Toni Morrison using private funds."
Colonial Lowcountry landowners experimented with cash crops ranging from tea to silkworms. African slaves brought knowledge of rice cultivation, which plantation owners cultivated and developed as a successful commodity crop by 1700. With the coerced help of African slaves from the Caribbean, Eliza Lucas, daughter of plantation owner George Lucas, learned how to raise and use indigo in the Lowcountry in 1747. Supported with subsidies from Britain, indigo was a leading export by 1750. Those and naval stores were exported in an extremely profitable shipping industry.
By the mid-18th century, Charles Town had become a bustling trade center, the hub of the Atlantic trade for the southern colonies. Charles Towne was also the wealthiest and largest city south of Philadelphia, in part because of the lucrative slave trade. By 1770, it was the fourth-largest port in the colonies, after Boston, New York, and Philadelphia, with a population of 11,000—slightly more than half of them slaves. By 1708, the majority of the colony's population was slaves, and the future state would continue to be a majority of African descent until after the Great Migration of the early 20th century.
Charles Town was a hub of the deerskin trade, the basis of its early economy. Trade alliances with the Cherokee and Creek nations insured a steady supply of deer hides. Between 1699 and 1715, colonists exported an average of 54,000 deer skins annually to Europe through Charles Town. Between 1739 and 1761, the height of the deerskin trade era, an estimated 500,000 to 1,250,000 deer were slaughtered. During the same period, Charles Town records show an export of 5,239,350 pounds of deer skins. Deer skins were used in the production of men's fashionable and practical buckskin pantaloons, gloves, and book bindings.
As Charles Town grew, so did the community's cultural and social opportunities, especially for the elite merchants and planters. The first theatre building in America was built in 1736 on the site of today's Dock Street Theatre. Benevolent societies were formed by different ethnic groups, from French Huguenots to free people of color to Germans to Jews. The Charles Towne Library Society was established in 1748 by well-born young men who wanted to share the financial cost to keep up with the scientific and philosophical issues of the day. This group also helped establish the College of Charles Towne in 1770, the oldest college in South Carolina. Until its transition to state ownership in 1970, this was the oldest municipally supported college in the United States.
On June 28, 1776, General Sir Henry Clinton along with 2,000 men and a naval squadron tried to seize Charles Towne, hoping for a simultaneous Loyalist uprising in South Carolina. When the fleet fired cannonballs, they failed to penetrate Fort Sullivan's unfinished, yet thick, palmetto-log walls. No local Loyalists attacked the town from the mainland side, as the British had hoped they would do. Col. Moultrie's men returned fire and inflicted heavy damage on several of the British ships. The British were forced to withdraw their forces, and the Americans renamed the defensive installation as Fort Moultrie in honor of its commander.
Clinton returned in 1780 with 14,000 soldiers. American General Benjamin Lincoln was trapped and surrendered his entire 5,400-man force after a long fight, and the Siege of Charles Towne was the greatest American defeat of the war. Several Americans who escaped the carnage joined other militias, including those of Francis Marion, the "Swamp Fox"; and Andrew Pickens. The British retained control of the city until December 1782. After the British left, the city's name was officially changed to Charleston in 1783.
Although the city lost the status of state capital to Columbia in 1786, Charleston became even more prosperous in the plantation-dominated economy of the post-Revolutionary years. The invention of the cotton gin in 1793 revolutionized the processing of this crop, making short-staple cotton profitable. It was more easily grown in the upland areas, and cotton quickly became South Carolina's major export commodity. The Piedmont region was developed into cotton plantations, to which the sea islands and Lowcountry were already devoted. Slaves were also the primary labor force within the city, working as domestics, artisans, market workers, and laborers.
The city also had a large class of free people of color. By 1860, 3,785 free people of color were in Charleston, nearly 18% of the city's black population, and 8% of the total population. Free people of color were far more likely to be of mixed racial background than slaves. Many were educated, practiced skilled crafts, and some even owned substantial property, including slaves. In 1790, they established the Brown Fellowship Society for mutual aid, initially as a burial society. It continued until 1945.
By 1820, Charleston's population had grown to 23,000, maintaining its black (and mostly slave) majority. When a massive slave revolt planned by Denmark Vesey, a free black, was revealed in May 1822, whites reacted with intense fear, as they were well aware of the violent retribution of slaves against whites during the Haitian Revolution. Soon after, Vesey was tried and executed, hanged in early July with five slaves. Another 28 slaves were later hanged. Later, the state legislature passed laws requiring individual legislative approval for manumission (the freeing of a slave) and regulating activities of free blacks and slaves.
In Charleston, the African American population increased as freedmen moved from rural areas to the major city: from 17,000 in 1860 to over 27,000 in 1880. Historian Eric Foner noted that blacks were glad to be relieved of the many regulations of slavery and to operate outside of white surveillance. Among other changes, most blacks quickly left the Southern Baptist Church, setting up their own black Baptist congregations or joining new African Methodist Episcopal Church and AME Zion churches, both independent black denominations first established in the North. Freedmen "acquired dogs, guns, and liquor (all barred to them under slavery), and refused to yield the sidewalks to whites".
Industries slowly brought the city and its inhabitants back to a renewed vitality and jobs attracted new residents. As the city's commerce improved, residents worked to restore or create community institutions. In 1865, the Avery Normal Institute was established by the American Missionary Association as the first free secondary school for Charleston's African American population. General William T. Sherman lent his support to the conversion of the United States Arsenal into the Porter Military Academy, an educational facility for former soldiers and boys left orphaned or destitute by the war. Porter Military Academy later joined with Gaud School and is now a university-preparatory school, Porter-Gaud School.
In 1875, blacks made up 57% of the city's population, and 73% of Charleston County. With leadership by members of the antebellum free black community, historian Melinda Meeks Hennessy described the community as "unique" in being able to defend themselves without provoking "massive white retaliation", as occurred in numerous other areas during Reconstruction. In the 1876 election cycle, two major riots between black Republicans and white Democrats occurred in the city, in September and the day after the election in November, as well as a violent incident in Cainhoy at an October joint discussion meeting.
Violent incidents occurred throughout the Piedmont of the state as white insurgents struggled to maintain white supremacy in the face of social changes after the war and granting of citizenship to freedmen by federal constitutional amendments. After former Confederates were allowed to vote again, election campaigns from 1872 on were marked by violent intimidation of blacks and Republicans by white Democratic paramilitary groups, known as the Red Shirts. Violent incidents took place in Charleston on King Street in September 6 and in nearby Cainhoy on October 15, both in association with political meetings before the 1876 election. The Cainhoy incident was the only one statewide in which more whites were killed than blacks. The Red Shirts were instrumental in suppressing the black Republican vote in some areas in 1876 and narrowly electing Wade Hampton as governor, and taking back control of the state legislature. Another riot occurred in Charleston the day after the election, when a prominent Republican leader was mistakenly reported killed.
On August 31, 1886, Charleston was nearly destroyed by an earthquake. The shock was estimated to have a moment magnitude of 7.0 and a maximum Mercalli intensity of X (Extreme). It was felt as far away as Boston to the north, Chicago and Milwaukee to the northwest, as far west as New Orleans, as far south as Cuba, and as far east as Bermuda. It damaged 2,000 buildings in Charleston and caused $6 million worth of damage ($133 million in 2006 dollars), at a time when all the city's buildings were valued around $24 million ($531 million in 2006 dollars).
Investment in the city continued. The William Enston Home, a planned community for the city's aged and infirm, was built in 1889. An elaborate public building, the United States Post Office and Courthouse, was completed by the federal government in 1896 in the heart of the city. The Democrat-dominated state legislature passed a new constitution in 1895 that disfranchised blacks, effectively excluding them entirely from the political process, a second-class status that was maintained for more than six decades in a state that was majority black until about 1930.
On June 17, 2015, 21-year-old Dylann Roof entered the historic Emanuel African Methodist Episcopal Church during a Bible study and killed nine people. Senior pastor Clementa Pinckney, who also served as a state senator, was among those killed during the attack. The deceased also included congregation members Susie Jackson, 87; Rev. Daniel Simmons Sr., 74; Ethel Lance, 70; Myra Thompson, 59; Cynthia Hurd, 54; Rev. Depayne Middleton-Doctor, 49; Rev. Sharonda Coleman-Singleton, 45; and Tywanza Sanders, 26. The attack garnered national attention, and sparked a debate on historical racism, Confederate symbolism in Southern states, and gun violence. On July 10, 2015, the Confederate battle flag was removed from the South Carolina State House. A memorial service on the campus of the College of Charleston was attended by President Barack Obama, Michelle Obama, Vice President Joe Biden, Jill Biden, and Speaker of the House John Boehner.
Charleston is known for its unique culture, which blends traditional Southern U.S., English, French, and West African elements. The downtown peninsula has gained a reputation for its art, music, local cuisine, and fashion. Spoleto Festival USA, held annually in late spring, has become one of the world's major performing arts festivals. It was founded in 1977 by Pulitzer Prize-winning composer Gian Carlo Menotti, who sought to establish a counterpart to the Festival dei Due Mondi (the Festival of Two Worlds) in Spoleto, Italy.
Charleston's oldest community theater group, the Footlight Players, has provided theatrical productions since 1931. A variety of performing arts venues includes the historic Dock Street Theatre. The annual Charleston Fashion Week held each spring in Marion Square brings in designers, journalists, and clients from across the nation. Charleston is known for its local seafood, which plays a key role in the city's renowned cuisine, comprising staple dishes such as gumbo, she-crab soup, fried oysters, Lowcountry boil, deviled crab cakes, red rice, and shrimp and grits. Rice is the staple in many dishes, reflecting the rice culture of the Low Country. The cuisine in Charleston is also strongly influenced by British and French elements.
The traditional Charleston accent has long been noted in the state and throughout the South. It is typically heard in wealthy white families who trace their families back generations in the city. It has ingliding or monophthongal long mid-vowels, raises ay and aw in certain environments, and is nonrhotic. Sylvester Primer of the College of Charleston wrote about aspects of the local dialect in his late 19th-century works: "Charleston Provincialisms" (1887) and "The Huguenot Element in Charleston's Provincialisms", published in a German journal. He believed the accent was based on the English as it was spoken by the earliest settlers, therefore derived from Elizabethan England and preserved with modifications by Charleston speakers. The rapidly disappearing "Charleston accent" is still noted in the local pronunciation of the city's name. Some elderly (and usually upper-class) Charleston natives ignore the 'r' and elongate the first vowel, pronouncing the name as "Chah-l-ston". Some observers attribute these unique features of Charleston's speech to its early settlement by French Huguenots and Sephardic Jews (who were primarily English speakers from London), both of whom played influential roles in Charleston's early development and history.[citation needed]

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