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 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 its parent route, U.S. Route 9 (US 9), in the town of Champlain and US 11 in the village of Rouses Point. While US 9 bypasses Rouses Point to the west, NY 9B veers east to serve the village and the shoreline of Lake Champlain. NY 9B is the northernmost section of the Lakes to Locks Passage, an All-American Road. Modern NY 9B was the original alignment