Lake Michigan is the second largest of the Great Lakes by volume and the only Great Lake entirely within the United States. Lake Michigan has more than 1,600 miles of shoreline.
The lake is approximately 118 miles wide and 307 miles long. The average depth is 279 feet. The deepest point is roughly 925 feet in the Chippewa Basin. Along its western shore, the Door Peninsula separates Green Bay from Lake Michigan.
Lake Michigan is hydrologically inseparable from Lake Huron, joined by the Straits of Mackinac. The Mackinac Bridge spans the Straits of Mackinac in northern Michigan.
Northern Lake Michigan consists of the colder, less developed upper Great Lakes region. The more temperate southern basin contains the cities of Milwaukee and Chicago.
On the western shore of Lake Michigan, the Sturgeon Bay Ship Canal is a popular area for ship spotting, photography, birding, and other activities.
In Chicago, the Chicago Area Waterway System (CAWS) allows vessel traffic to navigate between the Great Lakes and Mississippi River basins.
The annual withdrawal of water from Lake Michigan by the State of Illinois is limited by a U.S. Supreme Court decree. The U.S. Geological Survey (USGS) monitors flows in the CAWS as part of the Lake Michigan Diversion Accounting (LMDA) overseen by the U.S. Army Corps of Engineers, Chicago District.
Sleeping Bear Dunes National Lakeshore and other areas along the coast of Michigan make up the world’s largest collection of freshwater sand dunes. The tallest dune stands about 450 feet above the shore of Lake Michigan.
Designated in 2021, Wisconsin Shipwreck Coast National Marine Sanctuary extends from Wisconsin’s Port Washington to Two Rivers. The sanctuary encompasses 962 square miles of Lake Michigan and includes 36 known shipwreck sites. The project is co-managed by the National Oceanic and Atmospheric Administration (NOAA) and the state of Wisconsin.