The M Sixth Avenue Local is a rapid transit service in the New York City Subway's B Division. Its route emblem, or "bullet", is colored orange since it uses the IND Sixth Avenue Line in Manhattan. On weekdays, the M operates between 71st Avenue in Forest Hills, Queens, and Metropolitan Avenue in Middle Village, Queens, via the IND Queens Boulevard Line and Sixth Avenue, the Williamsburg Bridge, and the BMT Jamaica and Myrtle Avenue lines. This makes the M the only service that travels through the same borough via two different, unconnected lines.
The M short turns at Essex Street in the Lower East Side of Manhattan on weekends, and at Myrtle Avenue – Broadway in Brooklyn during nights. The M is the only non-shuttle service that has both of its full-run terminals in the same borough (Queens). The 71st Avenue and Metropolitan Avenue termini of the M route are 2.47 miles (3.98 km) apart, marking these the shortest geographic distances between termini for a New York City Subway non-shuttle service.