The M10 and M20 bus routes serve the northern and southern halves of the Eighth Avenue corridor, respectively.

The routes intersect in Upper Midtown Manhattan, between Lincoln Center and Columbus Circle.

[6] The M10 bus begins in Harlem at Frederick Douglass Boulevard (Eighth Avenue) roughly where 158th Street would be located, on the east side of the Polo Grounds Towers housing complex.

[8]: 79 The M20 begins service at Broadway and West 63rd Street in Lincoln Center, at Dante Park.

Eighth Avenue was made one-way northbound between Abingdon Square and Columbus Circle, and Hudson Street was made one-way northbound between Chambers Street and Abingdon Square.

[13][14][15][16] In 1962, when the Surface Company bought the route they put one bus service for the entire length.

Service began running north along Hudson Street and south along Seventh Avenue.

[20] On May 9, 1977, weekday limited-stop service began on the M10, operating northbound between 4 p.m. and 5:20 p.m., and southbound between 6:40 a.m. and 8:30 a.m..[21] The New York City Transit Authority proposed officially eliminating M10 Limited service along 145th Street and Lenox Avenue to Esplanade Gardens at 147th Street on December 30, 1986.

The official change would reroute these trips to the usual northern terminal at 159th Street, and would take effect in March 1987.

[6] On January 16, 2000, the M10 was split into two routes, with the northern section from Harlem to Penn Station still operating under the M10 designation, and the southern segment from Columbus Circle to Battery Park City being renamed the M20.

[25] In December 2002, the MTA announced plans to reroute the M20 from West Street to serve the northern portion of Battery Park City.

[26] Due to budget constraints during the Great Recession, M10 buses' southern terminus was truncated to Columbus Circle on June 27, 2010.

[8]: 73, 74, 79  The truncation, which saved $1.1 million annually, resulted in a significant drop in ridership on the M10, with riders instead using the M7, the M20, and the subway.