St. Marys River (Michigan–Ontario) St. Marys River (Michigan–Ontario) The St. Marys River (), sometimes written as the St. Mary's River, drains Lake Superior, starting at the end of Whitefish Bay and flowing southeast into Lake Huron, with a fall of . For its entire length it is an international border, separating Michigan in the United States from Ontario, Canada. The twin cities of Sault Ste. Marie, Ontario, and Sault Ste. Marie, Michigan are connected across the St. Marys River by the Sault Ste. Marie International Bridge. The St. Marys Rapids are just below the river's exit from Lake Superior and can be bypassed by
Sault Ste. Marie, Ontario city to Thunder Bay to the northwest and Sudbury to the east. The International Bridge connects downtown Sault Ste. Marie to Sault Ste. Marie, Michigan, becoming Interstate 75 on the American side. Interstate 75 continues south to Saginaw, Flint, and Detroit before crossing into Ohio, eventually terminating in Hialeah, Florida, near Miami. The International Bridge also directs traffic from the American side of the border via Sault Ste. Marie's new transport route that runs from the bridge to Second Line. This new limited-access roadway, known as "Carmen's Way" after the late MP Carmen Provenzano, will make it much easier for