The F train was the first New York City Subway service to run through the 63rd Street Tunnel.
The tunnel connects Manhattan and Queens beneath the East River and carries subway tracks as well as infrastructure for other transportation uses. The subway portion opened in 1989, linking the IND Queens Boulevard Line in Queens with the IND Sixth Avenue Line in Manhattan. F trains began using the route when it opened.
The tunnel was built to improve access between Queens and Midtown Manhattan, but its initial service pattern was limited by incomplete connections and low ridership. Later projects expanded the tunnel’s usefulness, including the Second Avenue Subway connection in Manhattan, which allowed the Q service to use the tunnel’s north side.
The F remains the principal service on the tunnel’s original subway connection. The Q’s later role is why some riders associate the tunnel primarily with the Q today.