Sault Ste. Marieis a city on theSt. Marys RiverinOntario, Canada, close to theUS-Canada border.To the south, across the river, is the United States and the city ofSault Ste. Marie, Michigan. These two communities were one city until a new treaty after theWar of 1812established 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 theInternational Bridge, which connectsInterstate 75on the Michigan side, and Huron Street (and former Ontario Secondary Highway 550B) on the Ontario side. Shipping traffic in theGreat Lakes system bypasses the Saint Mary's Rapids via the AmericanSoo Locks, the world's busiest canal in terms of tonnage that passes through it, while smaller recreational and tour boats use the CanadianSault Ste. Marie Canal.