The Staten Island Railway (SIR) is a rapid transit line in the New York City borough of Staten Island. It is owned by the Staten Island Rapid Transit Operating Authority (SIRTOA), a subsidiary of the Metropolitan Transportation Authority, and operated by the New York City Transit Authority Department of Subways. SIR operates 24 hours a day, seven days a week, providing local service between St. George and Tottenville, along the east side of the island. There is currently only one line on the island, and there is no direct rail link between the SIR and the New York City Subway system, but SIR riders do receive a free transfer to New York City Transit bus and subway lines, and the line is included on official New York City Subway maps. Commuters on the railway typically use the Staten Island Ferry to reach Manhattan. The line is accessible from within the Ferry Terminal, and most of its trains are timed to connect with the ferry. In 2023, the system had a ridership of 6,151,400, or about 19,500 per weekday as of the fourth quarter of 2023.

The R211 is a new technology train (NTT) New York City Subway car being built by Kawasaki Railcar Manufacturing for the B Division and the Staten Island Railway (SIR). They will replace two aging subway car models: all R44 cars on the Staten Island Railway and all R46 subway cars. The order is split into three parts: R211A and R211T cars for the subway and R211S cars for the SIR. The R211Ts employ open gangways between cars, allowing passengers to see and walk through the entire length of the train – a feature not present on the subway's other rolling stock. The base order consists of 535 cars, with options for up to 1,077 additional cars.