U.S. Route 9 (US 9) is a part of the United States Numbered Highway System that runs from Laurel, Delaware, to Champlain, New York. In New York, US 9 extends 324.72 miles (522.59 km) from the George Washington Bridge in Manhattan to an interchange with Interstate 87 (I-87) just south of the Canadian border in the town of Champlain. US 9 is the longest north–south U.S. Highway in New York. The portion of US 9 in New York accounts for more than half of the highway's total length.

Champlain is a town in Clinton County, New York, United States. The population was 5,754 at the 2010 census. The town is located on the western shore of Lake Champlain, near the northern end of Lake Champlain and is on the U.S./Canadian border.