Which strait connects Lake Michigan and Lake Huron at the same water level?

The Straits of Mackinac connect Lake Michigan and Lake Huron at essentially the same water level. Their open-water link allows the two basins to exchange water freely, so hydrologists often treat them as one system called Lake Michigan–Huron.

The straits lie between Michigan’s Upper and Lower Peninsulas. The main channel is roughly 5 miles wide and about 120 feet deep, while the surrounding lakes are vastly deeper. Water usually moves eastward toward Lake Huron, but wind, atmospheric pressure, and seiches can reverse the local flow.

The passage has long been an important Indigenous and fur-trade route. Its name derives from Mackinac Island; the Ojibwe name Michilimackinac is commonly interpreted as “Big Turtle.” Today, the Mackinac Bridge spans the straits, and icebreakers keep shipping routes open when winter ice forms.

A common mix-up is to name the Detroit River, which connects Lake St. Clair and Lake Erie, or the Niagara River, which connects Lake Erie and Lake Ontario. Neither is the Michigan–Huron connection.