North Tonawanda is a city in Niagara County, New York, United States. Its population was 31,568 at the 2010 census. It is part of the Buffalo–Ni…North Tonawanda is a city in Niagara County, New York, United States. Its population was 31,568 at the 2010 census. It is part of the Buffalo–Niagara Falls metropolitan statistical area. The city is named after Tonawanda Creek, its southern border.