The R9 was a New York City Subway car model, which was built by the American Car and Foundry Company and the Pressed Steel Car Company in 1940 for the Independent Subway System (IND) and its successors, which included the New York City Board of Transportation and the New York City Transit Authority. Identical to the preceding R7/As, the R9s had distinctive curved ends on the rollsign boxes and contained distinct 2CY air compressors not featured on the older cars in the R1–9 fleet. A total of 153 cars were built, numbered 1650–1802, and arranged as single units. They were the last R1–9 type cars that were ordered before the merger of the IND with the IRT and BMT in 1940.

The Independent Subway System was a rapid transit rail system in New York City that is now part of the New York City Subway. It was first constructed as the Eighth Avenue Line in Manhattan in 1932. It was originally also known as the Independent City-Owned Subway System (ICOSS) or the Independent City-Owned Rapid Transit Railroad (ICORTR).