Tonawanda is a city in Erie County, New York, United States. The population was 15,129 at the 2020 census. It is at the northern edge of Erie County, south across the Erie Canal from North Tonawanda, east of Grand Island, and north of Buffalo. It is part of the Buffalo-Niagara Falls metropolitan area.

The Erie Canal is a historic canal in upstate New York that runs east–west between the Hudson River and Lake Erie. Completed in 1825, the canal was the first navigable waterway connecting the Atlantic Ocean to the Great Lakes, vastly reducing the costs of transporting people and goods across the Appalachians. In effect, the canal accelerated the settlement of the Great Lakes region, the westward expansion of the United States, and the economic ascendancy of New York State. It has been called "The Nation's First Superhighway."