Background
Source: Wikipedia
The Interborough Rapid Transit Company (IRT) was the private operator of New York City's original underground 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 on June 12, 1940, along with the younger BMT and IND systems, to form the modern New York City Subway. The former IRT lines (the numbered routes in the current subway system) are now the A Division or IRT Division of the Subway.
