Nicknamed City Cars, the R1s were the first of five subway car classes collectively referred to as the R1–9 fleet, with future passenger stock orders – including contracts R4, R6, R7/A, and R9 – being virtually identical, with minor mechanical and cosmetic variations.

For their time, the R1s introduced several improvements to subway car design that greatly sped up the flow of passengers in and out of trains.

Future orders of subway cars, including those built for the A Division, would follow the R contract.

[1] The first R1 cars to see passenger service were twenty individual cars to serve for two eight-car trains plus spares that were placed in revenue service on the BMT Sea Beach Line from July 8 to November 1931 for testing and then returned to the IND the same year.

However, car 369, which was renumbered to 576 on October 3, 1969[4] and then to 1768 on August 27, 1973,[4] was transferred to the East New York Yard.