Michigan, Lake, the third largest of the Great Lakes, and the only one of the group wholly in the United States. Michigan, Indiana, Illinois, and Wisconsin border the lake. It covers 22,300 square miles (57,800 km2), has a maximum width of 118 miles (190 km), and is 321 miles (517 km) long. The surface is 577 feet (176 m) above sea level. The greatest depth is 922 feet (281 m). Green Bay, the largest arm, receives the Fox River.
The Illinois Waterway links Lake Michigan with the Mississippi River. Canadian and Atlantic shipping enter through the Straits of Mackinac, from Lake Huron. Goods shipped on the lake include grain, petroleum products, and iron ore and coal. The main ports are at Chicago, Indiana Harbor, and Milwaukee.
Lake Michigan was discovered in 1634 by Jean Nicolet, an explorer from New France (now Canada), who was looking for a water passage to the Pacific Ocean.