At over 1,600 miles long, the distance from Chicago to the Florida Keys, The Lake Michigan shoreline contains the largest lake fully within the the United States. Length = 307 miles, Width = 118 miles.

The Straits of Mackinac, Lake Michigan's only natural outlet, connects the lake with Lake Huron to the northeast; the Illinois Waterway links Lake Michigan with the Mississippi River and Gulf of Mexico. The Saint Lawrence Seaway has opened Lake Michigan to international trade.

Many islands are found in the northern part of the lake; the northern shorelines are indented, with Green Bay and Grand Traverse Bay the largest bays.

Prevailing westerly winds tempered by the lake give the eastern shore a moderate climate, making it a rich fruit belt and popular resort area. The southern part of the lake does not freeze over in the winter, but storms and ice halt interlake movement from December to April.

Lake Michigan, by volume, is the second largest Great Lake and the only one located totally within the United States. The northern part is in the colder less developed upper Great Lakes region. It is sparsely populated, except for the Fox River Valley, and is primarily covered with mixed wood forest. The more temperate southern basin of Lake Michigan is the most urbanized area in the Great Lakes system; it contains the Milwaukee and Chicago metropolitan areas. Southern-soils are typically fertile and amenable to agriculture.