Rapid Transit
While railways of any type may have portions of their tracks below, on, or above ground level, the term subway (or, depending on where in the world it is located, metro, underground or underground railway, or tube) is generally reserved for systems using the arrangement of cars described above and having most of their track underground. London's underground, which went into service in 1863, is the oldest in the world; initially steam-powered, it was fully electrified by 1896, the same year that the first subway began operating on the European continent in Budapest, Hungary. Boston installed (1898) the first subway in the United States; others followed in Paris (1900), Berlin (1902), New York (1904), Madrid (1919), Tokyo (1927), and Moscow (1935). Toronto's subway, completed in 1954, was the first in Canada; Montreal's subway was completed in 1966. By the beginning of the 21st cent. there were 95 subways in 59 countries, 11 of these in the United States—in addition to Boston and New York, there are subways in Atlanta (1979), Baltimore (1983), Chicago (1943), Cleveland (1955), Los Angeles (1993), Miami (1984), Philadelphia (1908), San Francisco (1972), and Washington, D.C. (1976).
Some subways consist of only a single line, but others, such as the Métropolitain in Paris, the New York City Transit system, and the London underground, are networks. The London system has the most track (256 mi/410 km), and the Moscow system carries the most passengers annually (3.1 billion). By far the largest underground transportation system in the United States is that of New York City. It carries 1.2 billion people and has more than 245 mi (393 km) of track; it also has 6,273 cars and 463 stations—more than any other system in the world. Moscow has an elaborate subway system with tunnels 15 to 20 ft (4.5 to 6 m) high instead of the usual 10 ft (3 m). Marble was used lavishly in constructing the stations, and Russia's best-known artists participated in their decoration.
In recent years concern over urban crowding and automotive air pollution has stimulated the construction and expansion of many rapid transit systems that incorporate automated operation and magnetic-card fare systems; examples are the Bay Area Rapid Transit system in California, the Metro system in Washington D.C., and a section of the London underground. See also mass transit.
See C. W. Cheape, Moving the Masses (1980); T. Rallis, City Transport in Developed and Developing Countries (1988); C. Hood, 722 Miles: The Building of the Subways and How They Transformed New York (1995); B. J. Cudahy, Under the Sidewalks of New York (2d rev. ed. 1996); S. Fischler, The Subway: A Trip Through Time on New York's Rapid Transit (1997).

