Sault Ste. Marie is a city at the St. Marys River in Ontario, Canada, close to the Canada–US border. It is the seat of the Algoma District and the third largest city in Northern Ontario, after Sudbury and Thunder Bay.
The Ojibwe, the indigenous Anishinaabe inhabitants of the area, call this area Baawitigong, meaning "place of the rapids." They used this as a regional meeting place during whitefish season in the St. Mary's Rapids.
To the south, across the river, is the United States and the Michigan city of the same name. These two communities were one city until a new treaty after the War of 1812 established the border between Canada and the United States in this area at the St. Mary's River. In the 20th century, the two cities are joined by the International Bridge, which connects Interstate 75 on the Michigan side, and Huron Street on the Ontario side. Shipping traffic in the Great Lakes system bypasses the Saint Mary's Rapids via the American Soo Locks, the world's busiest canal in terms of tonnage that passes through it, while smaller recreational and tour boats use the Canadian Sault Ste. Marie Canal.
French colonists referred to the rapids on the river as Les Saults de Ste.