Cars 9346–9523 and 9558–9769 were specifically purchased for service on the IRT Flushing Line ( trains), which was the closest line to the 1964 New York World's Fair. The cars were also referred to as "World's Fair" cars, or R36WFs (R36 World's Fair), and featured three-piece curved "picture" windows, unlike other IRT cars at the time. While in regular service, five two-car consists of these cars were coupled to one single R33S car to make 11-car trains for the 7 and <7> routes.