Lake Michigan the third largest lake in the Great Lakes. It is also the only Great Lake to lie entirely within the United States. The lake has Michigan as its eastern and northern boundary. Its western shores are in Illinois and Wisconsin. A small piece of Indiana touches the southeast corner.
Lake Michigan is more than 900 feet deep at some points. The largest arm of Lake Michigan is Green Bay, which terminates at the Wisconsin city of Green Bay. The largest cities on the lake are Chicago and Milwaukee. The lake drains towards the Atlantic Ocean through Lake Huron.