Along with the BMT and IRT, one of the three former divisions of the New York City Subway and the only one owned by the city from its opening. First section opened in 1932 under Eighth Avenue, consisting of the now world-famous A train.

The first phase of the IND was completed in 1953. A second phase had been planned, however the Great Depression and then World War II prevented construction. The IND was merged with the BMT in 1967.