Plattsburgh is a city in and the seat of Clinton County, New York, United States. The population was 19,989 at the 2010 census. The population of the unincorporated areas within the surrounding (and separately incorporated) Town of Plattsburgh was 11,870 as of the 2010 census, making the combined population for all of Plattsburgh to be 31,859. Plattsburgh lies just to the northeast of Adirondack Park, immediately outside of the park boundaries. It is the second largest community in the North Country region (after Watertown), and serves as the main commercial hub for the sparsely populated northern Adirondack Mountains.