The town occupies the northeastern corner of Clinton County and the state of New York.

Nearby Lake Champlain was an important military and trade route during the colonial period.

The lake and the town were named in honor of Samuel de Champlain, who first surveyed the area in 1609.

The Champlain Port of Entry on Interstate 87 is one of the four most important commercial gateways on the northern border,[clarification needed] connecting New York City to the south with Montreal to the north, via Quebec Autoroute 15.

[2] Lake Champlain and the Richelieu River are on the eastern edge of the town, which shares a border with Grand Isle County, Vermont.

The town line to the north is the international border with Saint-Bernard-de-Lacolle, Quebec, Canada.

The 176-mile (283 km) Adirondack Northway (I-87) is a major north-south highway that begins at the Canadian border at Champlain and travels south to Albany, connecting to the New York State Thruway.