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
U.S. Route 11 in New York south of Champlain, bypassing the village completely. In northeastern St. Lawrence County, US 11 originally served the neighboring hamlets of Brasher Falls and Winthrop. The route left its modern alignment in Stockholm (at Stockholm Center) and rejoined it in Lawrence (at Coteys Corner). On September 1, 1982, ownership and maintenance of CR 110, a county road extending from Stockholm Center to Coteys Corner on a direct east–west routing, was transferred from St. Lawrence County to the state of New York as part of a highway maintenance swap between the two levels of government and the village of Canton. The new