The M5 and M55 bus routes constitute a public transit corridor in Manhattan, New York City, running along the Fifth / Sixth Avenues / Riverside Drive Line as well as the southern portion of the Broadway Line after the discontinuation of the M6. The routes primarily run along Broadway, Fifth and Sixth Avenues, and Riverside Drive from South Ferry, Lower Manhattan to Washington Heights. The M5 covers the northern portion of the route north of 31st Street, while the M55 operates along the southern portion of the route south of 44th Street. The two routes overlap in Midtown Manhattan. The portion along Broadway south of East 8th Street was originally a streetcar line.
The whole line was a single route, the M5, until January 2017, when the M55 was created.