The Broadway Line is a surface transit line in Manhattan, New York City, running mainly along 42nd Street and Broadway from Murray Hill to Harlem. Formerly a streetcar line operated by the Third Avenue Railway, it is now the M104 bus route operated by the New York City Transit Authority, a subsidiary of the Metropolitan Transportation Authority. This bus route no longer runs along the entire route of the former streetcar.

The Third Avenue Railway System (TARS), founded 1852, was a streetcar system serving the New York City boroughs of Manhattan and the Bronx along with lower Westchester County. For a brief period of time, TARS also operated the Steinway Lines in Long Island City.