The R33S (also known as R33 World's Fair or R33WF) was a New York City Subway car that was built by St. Louis Car Company in 1963 for the IRT A Division. They were purchased for service on the IRT Flushing Line (7 and <7> trains), which was the closest line to the 1964 New York World's Fair. A total of 40 cars were built, arranged as single cars. While in regular service, each R33S was coupled to five two-car consists of R36 cars to make 11-car trains for the 7 and <7> routes.