Interborough Rapid Transit Company

The Interborough Rapid Transit Company (IRT) was the first operator of the original underground New York City Subway line that opened in 1904, as well as other earlier railways and rapid transit lines in New York City. The company was bought by New York City in June 1940. The former IRT lines (the numbered lines in the current subway system) are now the A Division or IRT Division of the Subway.

The following services are or were part of the IRT or MTA IRT Division:

Line 1: Seventh Avenue Local
Line 2: Seventh Avenue Express
Line 3: Seventh Avenue Express
Line 4: Lexington Avenue Express
Line 5: Lexington Avenue Express
Line 6: Lexington Avenue Local
Line 7: Flushing Express and Local
Line S: 42nd Street Shuttle