Which river connects Lake Superior to Lake Huron?

The St. Marys River connects Lake Superior to Lake Huron.

This international river flows for about 120 kilometres from the eastern end of Lake Superior to Lake Huron. It forms part of the boundary between Ontario, Canada, and Michigan, United States. Rapids near Sault Ste. Marie once made navigation difficult, but modern canals and locks allow large vessels to pass between the lakes.

The Soo Locks are the best-known navigation feature on the river. They enable ships to overcome the elevation difference between Lake Superior and the lower Great Lakes. The locks are especially important for transporting iron ore, grain, coal, and other bulk cargo through the Great Lakes–St. Lawrence waterway.

The St. Marys River should not be confused with the St. Clair River, which connects Lake Huron with Lake St. Clair and then Lake Erie through the Detroit River. Together, these rivers form part of the connected Great Lakes drainage route to the Atlantic Ocean.