Interstate 81 in New York

Interstate 81
Map of New York with I-81 highlighted in red
Route information
Maintained by NYSDOT and the Thousand Islands Bridge Authority
Length:	183.62 mi (295.51 km)
Existed:	August 14, 1957 – present
Major junctions
South end:	I-81 at the Pennsylvania state line near Binghamton
	I-86 / NY 17 in Binghamton I-88 near Binghamton NY 13 in Cortland I-90 / New York Thruway near Syracuse NY 104 near Mexico NY 3 near Watertown
North end:	Highway 137 at the Canadian border near Wellesley Island
Highway system
Interstate Highway System Main Auxiliary Suffixed Business New York Highways Interstate U.S. State Reference Parkways ← NY 80 NY 81 →

Interstate 81 (I-81) is a part of the Interstate Highway System that runs from Interstate 40 at Dandridge, Tennessee, to the Thousand Islands International Bridge at Wellesley Island in New York, beyond which a short stub links it to Ontario Highway 401. In the U.S. state of New York, I-81 extends 183.62 miles (295.51 km) from the Pennsylvania state line southeast of Binghamton to the Canadian border at Wellesley Island northwest of Alexandria Bay. The freeway runs north–south through Central New York, serving the cities of Binghamton, Syracuse, and Watertown. It passes through the Thousand Islands in its final miles and crosses two bridges, both part of the series of bridges known as the Thousand Islands Bridge.

South of Watertown, I-81 closely parallels U.S. Route 11 (US 11), the main north–south highway in Central New York prior to the construction of I-81. At Watertown, US 11 turns northeastward to head across New York's North Country while I-81 continues on a generally northward track to the Canadian border. From there, the road continues into the province of Ontario as Highway 137, a short route leading north to the nearby Highway 401.