Washington County, New York is part of the Great Appalachian Valley (also known simply as the 'Great Valley') which is a long narrow valley strip often between tall mountain ranges. The county transitions from the Taconic Mountains to the Adirondack Mountains, and from the Lake Champlain Valley to Hudson River Valley. Much of the county is part of the slate valley of the Upper Taconic Mountains (Taghkanic, meaning 'in the trees'). The eastern boundary of Washington County is the New York–Vermont border, part of which is Lake Champlain. This is also the border with New England proper. The northern end of the county is
Champlain, New York States border at Champlain and travels south to Albany, connecting to the New York State Thruway. U.S. Route 9 parallels I-87, and U.S. Route 11 runs east-west across the town. U.S. Route 2 intersects US-11 by Rouses Point. New York State Route 9B intersects US-11 in the northeast and US-9 in the southern part of Champlain, providing a highway closer to Lake Champlain. New York State Route 276 partly runs along the international border. As of the 2000 census, there were 5,791 people, 2,386 households, and 1,562 families residing in the town. The population density was 113.1 people per square