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. (The anglicized form of this name, Bawating, is used in institutional and geographic names in the area.)

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 21st century, the two cities are joined by the International Bridge, which connects Interstate 75 on the Michigan side, and Huron Street (and former Ontario Secondary Highway 550B) 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. Marie and the village name was derived from that. The rapids and cascades of the St. Mary’s River descend more than 6 m (20 ft) from the level of Lake Superior to the level of the lower lakes. Hundreds of years ago, this slowed shipping traffic, requiring an overland portage of boats and cargo from one lake to the other. The entire name translates to “Saint Mary’s Rapids” or “Saint Mary’s Falls”. The word sault is pronounced in French, and in the English pronunciation of the city name. Residents of the city are called Saultites.