Cornwall is a city in eastern Ontario, Canada, and the seat of the United Counties of Stormont, Dundas and Glengarry. Cornwall is Ontario's easternmost city, located on the Saint Lawrence River, in the Quebec City–Windsor Corridor along Ontario Highway 401, and is the urban center for surrounding communities, including Long Sault and Ingleside to the west, Mohawk Territory of Akwesasne to the south, St. Andrew's and Avonmore to the north, and Glen Walter, Martintown, Williamstown, and Lancaster to the east.
Cornwall lies on the 45th parallel, approximately 62 miles (99.78 kilometers) southeast of Ottawa, the national capital, 75 miles (120.7 kilometers) southwest of Montreal, Quebec's largest city, and 270 miles (434.52 kilometers) northeast of Toronto, the provincial capital and Canada's largest city. It is named after the English Duchy of Cornwall; the city's coat of arms is based on that of the duchy with its colours reversed and the addition of a "royal tressure", a Scottish symbol of royalty.