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, Michigan split between Canadian Pacific and Canadian National Railway (CN). CN operates the rail lines and the bridge in the Sault Ste. Marie area that were formerly part of the Soo Line. The Sugar Island Ferry provides automobile and passenger access between Sault Ste. Marie and Sugar Island, formerly a center of maple sugaring. The short route that the ferry travels crosses the shipping channel. Despite the high volume of freighter traffic through the locks, freighters typically do not dock in the Sault. However, the city hosts tugs, a tourist passenger ferry service, and a Coast Guard station along the shoreline