Interborough Rapid Transit Company

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.