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
Ticonderoga (CDP), New York the Vermont border. The community lies between Lake George and Lake Champlain on the site of a portage between the two lakes, previously guarded by historic Fort Ticonderoga. The waterway running through this portage is called the La Chute River, which drains the outflow of Lake George into Lake Champlain, and it contains a waterfall at the eastern edge of the hamlet. During the summer, a diesel-powered cable ferry connects the community to Shoreham, Vermont. The junction of New York State Route 9N, New York State Route 74, and New York State Route 22 is at the northern edge of