History: The New York City Subway, United States

The system's stations are located throughout the boroughs of Manhattan, Brooklyn, Queens and the Bronx. Staten Island has a rail line, the Staten Island Railway, which opened in 1860 and uses R44 subway cars, but has no links to, and is not officially considered part of the subway, though it has been included on all official Subway Maps since 1998.
All services pass through Manhattan except for the Franklin Avenue Shuttle in Brooklyn, Rockaway Park Shuttle in Queens, and Brooklyn–Queens Crosstown Local (G train) connecting Brooklyn and Queens. All but two of the 468 stations of the subway are served 24 hours a day. Contrary to its name, the New York City Subway system is not entirely underground; large portions of the system (especially outside of Manhattan) are elevated, on embankments, or in open cuts. A few stretches of track run at ground level.
In 2005, the New York City Subway hit a 50-year record in usage with a ridership of 1.45 billion. The trend toward higher ridership continued into 2008; MTA released figures that subway use was up 6.8 percent for January and February as higher gasoline prices encouraged riders to use mass transit over automobiles.
According to the United States Department of Energy, energy expenditure on the New York City Subway rail service was 3492 BTU/passenger mile (2289 kJ/passenger km) in 1995. This compares with 3702 BTU/passenger mile (2427 kJ/passenger km) for automobile travel. However, the figure for automobiles is averaged over the entire United States. Driving a car in New York City is significantly less efficient due to the highly urbanized environment.