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 the fluid environment changed during and after the War of 1812 between Britain and the United States. Trade dropped during the war and on July 20, 1814 an American force destroyed the North West Company depot on the north shore of the St. Marys River. Since the Americans were unable to capture Fort Mackinac, the British forces retained control of Sault Ste. Marie. In 1870, the United States refused to give the steamer "Chicona", carrying Colonel Garnet Wolseley, permission to pass through the locks at Sault Ste Marie. In order to control their own water passage, the Canadians constructed the