M17 or M-17 may refer to:
The 14th Street Crosstown Line is a public transit line in Manhattan, New York City, United States, running mostly along 14th Street from Chelsea to the Lower East Side. Originally a streetcar line, it is now the M14 bus route, operated by the New York City Transit Authority. The line's two variants, the M14A and M14D, use Avenue A and Avenue D respectively from 14th Street south into the Lower East Side.
The tracks were built by several companies and pieced together by the Metropolitan Street Railway by 1899. The Bleecker Street and Fulton Ferry Railroad built the 14th Street tracks west of 9th Avenue, the Central Crosstown Railroad built from 9th Avenue to Union Square, and the Forty-Second Street and Grand Street Ferry Railroad built from Union Square to Avenue A and south on Avenue A. The Metropolitan Crosstown built a short connection at Union Square to connect the two halves, and tracks north on 11th Avenue to the West 23rd Street Ferry.
When the Williamsburg Bridge opened in 1904, 14th Street cars were rerouted to use the bridge (running east on Delancey Street from the one-way pair of Clinton Street northbound and Essex Street southbound), running as the 14th Street-Williamsburg Bridge Line until 1911. Buses were substituted for streetcars by the New York City Omnibus Corporation on April 20, 1936. That company changed its name to Fifth Avenue Coach Lines in 1956; the Manhattan and Bronx Surface Transit Operating Authority took over operations in 1962.
The M16 was a 4.5-inch (110 mm) spin-stabilized unguided rocket developed by the United States Army during the Second World War. Entering service in April 1945 to replace the earlier fin-stabilised M8 rocket, it was used late in the war and also during the Korean War before being removed from service.
Developed during the latter stages of the Second World War, the M16 was the first 4.5-inch (110 mm) unguided, spin-stabilized rocket to be standardized for production by the United States Army.31 inches (790 mm) in length, it could hit targets as far as 5,200 yd (4,800 m) from its launcher. The M16 was launched from T66 "Honeycomb" 24-tube launchers, and could also be fired from 60-tube "Hornet's Nest" launchers. The United States Marine Corps developed launching systems for the M16 rocket as well, capable of being fitted to standard 3/4 and 2.5-ton trucks. A version of the M16 rocket for single launchers, the M20, was developed as a derivative; practice rounds designated M17 and M21 were also manufactured.