The Detroit River is an international river in North America. The river, which forms part of the international border between the U.S. state of Michigan and the Canadian province of Ontario, flows west and south for 24 nautical miles from Lake St. Clair to Lake Erie as a strait in the Great Lakes system. The river divides the metropolitan areas of Detroit, Michigan, and Windsor, Ontario—an area collectively referred to as Detroit–Windsor. The Ambassador Bridge, the Detroit–Windsor Tunnel, the Gordie Howe International Bridge, and the Michigan Central Railway Tunnel connect the cities.