The 6 Lexington Avenue/Pelham Local and <6> Lexington Avenue Local/Pelham Express are two rapid transit services in the New York City Subway's A Division. Their route emblems, or "bullets", are colored green since they use the IRT Lexington Avenue Line in Manhattan. Local service is denoted by a (6) in a circular bullet, and express service is denoted by a <6> in a diamond-shaped bullet.
6 trains operate local at all times between Pelham Bay Park in the Bronx and Brooklyn Bridge – City Hall in Lower Manhattan. During weekdays in the peak direction, <6> Pelham Express trains replace 6 Pelham Local ones north of Parkchester, and run express between that station and Third Avenue – 138th Street. During this time, 6 Pelham locals short turn at Parkchester (except for peak-direction <6> Express trains that return in the opposite direction as 6 Local trains).
On October 27, 1904, local and express service opened on the original subway in Manhattan, following the route of the present IRT Lexington Avenue Line from City Hall to Grand Central–42nd Street. From there, the service traveled west on 42nd Street on the route of the present 42nd Street Shuttle, and then north on the present IRT Broadway–Seventh Avenue Line to 145th Street.
The current "H" configuration—with separate services along Lexington Avenue and Broadway – Seventh Avenue—was introduced in 1917. Full Lexington Avenue local service from City Hall to 125th Street opened on July 17, 1918. On August 1, 1918, Third Avenue–138th Street opened with trains running between there and City Hall, making all stops.
On January 17, 1919, trains were extended from 138th Street to Hunts Point Avenue, and on May 30, 1920, 6 service was extended to East 177th Street. On October 24, 1920, 6 service was extended again to Westchester Square. On December 20, 1920, 6 service was extended to Pelham Bay Park. From that point on, the current 6 service was formed. The City Hall loop station closed with the former Brooklyn Bridge station (renamed to Brooklyn Bridge–City Hall) being the permanent southern terminal. However, the 6 train still uses the loop to get from the southbound to the northbound local track at Brooklyn Bridge-City Hall.