| Box Width: | 300px |
| Subheader: | 42nd Street Crosstown |
| System: | MTA Regional Bus Operations |
| Operator: | New York City Transit Authority |
| Garage: | Michael J. Quill Depot |
| Vehicle: | New Flyer Xcelsior XD40 New Flyer Xcelsior XE40 Nova Bus LFS HEV |
| Open: | November 17, 1946 1901 (streetcar) |
| Close: | November 17, 1946 (streetcar) |
| Locale: | Manhattan, New York, U.S. |
| Communities: | East Midtown, Midtown, West Midtown |
| Start: | East Side/United Nations - 41st Street & First Avenue |
| Via: | 42nd Street |
| End: | West Midtown/Circle Line Sightseeing Cruises – Twelfth Avenue & 42nd Street (Pier 83) |
| Length: | 2.2miles |
| Otherroutes: | M50 49th/50th Streets Crosstown |
| Day: | All times |
| Timetable Link: | M42 |
| Annualpatronage: | 2,384,180 (2023)[1] |
| Transfers: | Yes |
| Map State: | collapsed |
| Previous Line: | M35 |
| Next Line: | M50 |
The 42nd Street Crosstown Line is a public transit line in Manhattan, running primarily along 42nd Street in Midtown Manhattan. Originally a streetcar line, it is now the M42 bus route, operated by the MTA Regional Bus Operations under the New York City Transit Authority brand.
The 42nd Street Crosstown Line, operated by the Third Avenue Railway, ran along 42nd Street from Pier 83, located at the west end of 42nd Street to First Avenue and 42nd Street. The line ran under the designation X42, with X being used as a prefix for the Third Avenue Railway's crosstown routes.[2]
The M42 utilizes the same route as the streetcar, except that it loops around on its eastern end using the FDR Drive, 41st Street and First Avenue.
Originally chartered in 1878, the Forty-Second Street, Manhattanville & St. Nicholas Railway started service with horsedrawn carriages in 1884, with the Third Avenue Railway acquiring the line in 1896, and alongside it, the streetcar line. From 1898 to 1901, the line underwent the process of electrification. On November 17, 1946, the streetcar line was replaced by the Surface Transportation Corporation's, the bus-operating subsidiary of the Third Avenue Railway, M106 bus route.[3] On March 30, 1986, the M106 was re-designated as the M42.[4] On June 27, 2010, due to a budget crisis, service on the Javits Center branch was discontinued. This change was estimated to annually save $200,000.[5]