List of New York City Subway lines

In the New York City Subway nomenclature, a "line" refers to the physical trackage used by trains that are used by numbered or lettered "services"; the services that run on certain lines change periodically.

Since 1979, each service's color corresponds to the line it primarily uses in Midtown Manhattan[original research?

The following list shows the connections between the different divisions of the New York City Subway.

[15] Many of the New York City Subway's lines have express tracks, unused in revenue service and generally only used for re-routes.

[16] Despite “subway” implying underground travel, the following segments are located above ground or at grade level[17] and comprise about 40% of the trackage.

[18] At minimum, in normal revenue service, all lines have two tracks, with one exception: the BMT Franklin Avenue Line has a single track between Franklin Avenue and Park Place.

The third track, when in use, is generally for peak-direction express service or reroutes, with exceptions noted below.

The following New York City Subway lines are either entirely defunct or have major portions no longer in service.

A schematic map of New York City's subway lines (i.e., Sea Beach, West End, ...) as opposed to services (i.e., N, D, ...).
The Queens Boulevard viaduct of the IRT Flushing Line
A map of the New York City Subway by line placement. Underground is in orange. Elevated, at-grade, embankment, open-cut is in blue.
A map of the New York City Subway by the number of tracks on line segments.