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 International Bridge Sault Ste. Marie International Bridge The Sault Ste. Marie International Bridge spans the St. Marys River between the United States and Canada connecting the twin cities of Sault Ste. Marie, Michigan and Sault Ste. Marie, Ontario. The bridge is operated by the International Bridge Administration under the direction of the Sault Ste. Marie Bridge Authority, a bi-national governing body consisting of four directors appointed by the Governor of Michigan and four appointed by the Canadian government-owned Federal Bridge Corporation. The Sault Ste. Marie International Bridge is the tenth-busiest passenger crossing on the Canada–United States border, and the only land crossing