Plattsburgh is a city in and county 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 Town of Plattsburgh was 11,870 as of the 2010 census; making the population for the immediate Plattsburgh, New York Region 31,859. The city of Plattsburgh is located entirely within the original boundaries of the town of Plattsburgh and is in the North Country region of the northeastern part of the state.