Which strait connects Lake Michigan and Lake Huron?

The Straits of Mackinac connect Lake Michigan and Lake Huron.

This waterway lies between Michigan’s Upper and Lower peninsulas. It is about 8 kilometres wide at its narrowest point and has long been important for navigation, fishing, trade, and transportation. The Mackinac Bridge crosses the straits and links the two peninsulas by road.

The straits are relatively deep and allow substantial water exchange between the two lakes. Because Lake Michigan and Lake Huron have nearly identical water levels, scientists sometimes treat them as one hydrologic lake, known as Michigan–Huron. Their separate names remain firmly established in geography and everyday use.

The Straits of Mackinac are not the same as the St. Marys River. The St. Marys River carries water from Lake Superior into Lake Huron, while the straits provide the connection between Michigan and Huron. Both routes are part of the Great Lakes navigation system.