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 Town of Plattsburgh was 11,870 as of the 2010 census, making the population for the immediate Plattsburgh region 31,859.

The City of Plattsburgh is within the boundaries of the original Town of Plattsburgh and is in the North Country region of the U.S. state of New York.

The City of Plattsburgh is the population center and county seat at the heart of the Plattsburgh micropolitan statistical area (MSA) - population 82,128 as of the 2010 Census. A statistical area representing the greater Plattsburgh region (as defined by the U.S. government), the Plattsburgh MSA includes all communities in the immediate Clinton County, New York area.

Beginning with Samuel de Champlain's expedition into the Lake Champlain valley in 1609, the Plattsburgh region began to come under the French influence and later passed under English and finally American control. The early French contact and its closeness to Quebec made this an historically French area. Located in the extended fur trade network in the Montreal hinterland, the Plattsburgh area was the realm of the coureur des bois, who served the larger trading hub in Montreal.

Although Plattsburgh is a relatively new city, the surrounding area was settled during the mid-to-late 17th century. A permanent French settlement was hampered by the threat of conflict with the Iroquois, but French missionaries began living among the indigenous population as early as 1609. Moreover, the area near Plattsburgh is notable for being the site of an indigenous village. The local Catholic Churches also used to be run by Bishops of Quebec until 1808, when they were transferred to American Pastoral Care. As of 2013, trends are forcing Catholic churches and schools to consolidate.

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