The
Interborough Rapid Transit Company (
IRT) was the
private operator of the original underground
New York City Subway line that opened in 1904, as well as earlier
elevated railways and additional
rapid transit lines in
New York City. The IRT was purchased by the 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.