While US 9 bypasses Rouses Point to the west, NY 9B veers east to serve the village and the shoreline of Lake Champlain.

At Coopersville, the first named location along NY 9B, the highway crosses the Great Chazy River and turns to follow a more easterly routing toward Lake Champlain.

NY 9B reaches the shoreline one mile (1.6 km) later, at which point the route makes a sharp turn to the north to follow the western edge of Lake Champlain.

It serves a handful of lakeside homes before passing Point au Fer, a peninsula protruding southeastward into the lake.

Its former alignment to Rouses Point was redesignated as NY 9B,[2][3] which initially continued north along Lake Street to the Canadian border by way of an overlap with US 11.