Plattsburg is a city in and the county seat of Clinton County, Missouri and is part of the Kansas City metropolitan area in the western part of th…Plattsburg is a city in and the county seat of Clinton County, Missouri and is part of the Kansas City metropolitan area in the western part of the state, within the United States. It developed along the Little Platte River. As of the 2020 census, the city population was 2,222.