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
New York State Route 9B in the mid-1940s to bypass Rouses Point to the west and proceed north through the village of Champlain on its way to Canada. Its former alignment to Rouses Point was redesignated as NY 9B, which initially continued north along Lake Street to the Canadian border by way of an overlap with US 11. The overlap remained in place as late as 1979; it was eliminated by 1993. New York State Route 9B New York State Route 9B (NY 9B) is a state highway located within Clinton County, New York, in the United States. The route serves as a connector between