The IND Queens Boulevard Line, sometimes abbreviated as QBL, is a line of the B Division of the New York City Subway in Manhattan and Queens, New York City, United States. The line, which is underground throughout its entire route, contains 23 stations. The core section between 50th Street in Hell's Kitchen, Manhattan, and 169th Street in Jamaica, Queens, was built by the Independent Subway System (IND) in stages between 1933 and 1940, with the Jamaica–179th Street terminus opening in 1950. As of 2015, it is among the system's busiest lines, with a weekday ridership of over 460,000 people.

The 50th Street station is a bi-level station on the IND Eighth Avenue and Queens Boulevard Lines of the New York City Subway, located at 50th Street and Eighth Avenue in the Hell's Kitchen neighborhood of Manhattan. The lower level, on the Queens Boulevard Line, is served by the E train at all times, and the upper level, on the Eighth Avenue Line, is served by the C at all times except late nights and the A during late nights.