Cornwall, industrial city (1991 pop. 47,137), SE Ont., Canada, on the St. Lawrence River. It manufactures cotton and rayon textiles, paper, chemicals, furniture, and electronic equipment. The Canadian headquarters of the St. Lawrence Seaway Authority and a campus of St. Lawrence College are in Cornwall. The Akwesasne (in the United States, St. Regis) Mohawk reservation lies across the river on the Quebec–New York boundary.