The first streetcars were pulled by horses in 1832 in New York City. The low friction of a metal wheel on a metal rail permitted a given horsepower to move more people more quickly than was otherwise possible. With substantial urban growth in the 19th century, cities throughout the world began to utilize the horse-drawn streetcar.
The components of the electric streetcar were developed in the 1880s, and a practical system of electric railway traction was developed in 1888. By World War I more than 40,000 km (25,000 mi) of street railways were operating in the United States. The streetcar helped shape American cities, because city structures -businesses, housing, schools, entertainment facilities- were built along streetcar lines.
Growing competition from automobiles in the early 1920s began the decline of the streetcar -although the development of the so-called PCC car, a thoroughly modern vehicle of great comfort and speed, delayed the complete demise of the system. Many PCC cars continued to operate in the 1980s, and a few are still in service.
A modern offshoot of the traditional streetcar is the electric-powered light rapid-transit vehicle, which runs on fixed rails on its own right-of-way, can be operated underground as well as on street level, and may consist of several cars in a train. Light rapid-transit vehicles can run at much higher speeds than the traditional streetcar. A conventional streetcar line can move about 6,000 to 9,000 riders per track per hour; light rapid transit has a comparable capacity of up to 25,000 riders.
Rapid transit systems are seen by many as a relatively low-cost, high-efficiency answer to highway traffic congestion and its consequent air pollution. Such systems are common in Europe, and are now in use in many large American cities. New Jersey's Hudson-Bergen line, which will cost some $1.1 billion and stretch 33 km (20.5 mi) along the most densely urbanized portion of New Jersey's Hudson River coastline when it is completed in 2010, will carry 25,000 riders per day to commuter rail stations and cross-Hudson ferries, and will open for development long-neglected areas of east New Jersey. More than three-fourths of its track lies on old railbeds that once carried trolleys, back in the days before automobiles became the prime mode of travel.
