Plattsburgh is a city in Clinton County, New York, United States, situated on the north-western shore of Lake Champlain. The population was 19,841 at the 2020 census. The population of the unincorporated areas within the surrounding (and separately incorporated) Town of Plattsburgh was 11,886 as of the 2020 census, making the combined population for all of greater Plattsburgh to be 31,727. 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. The land around what is referred to as Plattsburgh was previously inhabited by the Iroquois, Western Abenaki, Mohican and Mohawk people. Samuel de Champlain was the first ever recorded European that sailed into Champlain Valley and later claimed the region as a part of New France in 1609.

​

Plattsburgh was the site of the amphibious Battle of Plattsburgh in the War of 1812, a key American victory that marked the end of hostilities in the Northern United States. The city is home to SUNY Plattsburgh, a liberal arts university which is a part of the State University of New York (SUNY) system and Clinton Community College, which is also part of the SUNY System.