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 centre 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.