New York State Route 12E (NY 12E) is a state highway located entirely within the northwestern part of Jefferson County in northern New York, USA. Officially, the southern terminus of NY 12E is at NY 12 in the city of Watertown; however, its signed terminus is at NY 12F in the village of Brownville. Its northern terminus, both signed and official, is at NY 12 in the village of Clayton. NY 12E diverges westward and then eastward to follow the shoreline of Lake Ontario, unlike NY 12, which follows a direct north–south routing between Watertown and Clayton. The portion of NY 12E north of its junction with NY 180 is part of the Seaway Trail, a National Scenic Byway.