>>1067208Many rapid transit systems run relatively static routings, so that a train "line" is more or less synonymous with a train "route". In New York City, however, routings change often because of changes in the availability of connections or the setup of service patterns. Within the nomenclature of the subway, the "line" describes the physical railroad track or series of tracks that a train "route" uses on its way from one terminal to another. "Routes" (also called "services") are distinguished by a letter or a number and "Lines" have names. They are also designations for trains, as exemplified in the Billy Strayhorn song "Take the "A" Train".
There are 25 train services in the subway system, including three short shuttles. Each route has a color and a local or express designation representing the Manhattan trunk line of the particular service. The color lime green is exclusively assigned to the Crosstown Line route, which operates entirely outside Manhattan, while the shuttles are all assigned dark slate gray. The lines and services are not referred to by color (e.g., Blue Line or Green Line) by native New Yorkers or by most New York City residents, but out-of-towners and tourists often refer to the subway lines by color.
