Niagara County is a county in the U.S. state of New York. As of the 2010 census, the population was 216,469. The county seat is Lockport. The county name is from the Iroquois word Onguiaahra; meaning the strait or thunder of waters. Niagara County is part of the Buffalo-Niagara Falls metropolitan area, and across the Canada–US border is the province of Ontario.
It is the location of Niagara Falls and Fort Niagara, and has many parks and lake shore recreation communities. In the summer of 2008, Niagara County celebrated its 200th birthday with the first town of the county, Town of Cambria.
The county borders Lake Ontario to the north, Orleans County to the east, Genesee County to the southeast, Erie County to the south, and Ontario in Canada to the west.