Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. The other four Great Lakes are shared by the US and Canada. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron (and is slightly smaller than the U.S. state of West Virginia). Hydrologically, the lake is a large bay of Lake Michigan–Huron, having the same surface elevation as Lake Huron. It is bounded, from west to east, by the U.S. states of Wisconsin, Illinois, Indiana, and Michigan.
Lake Michigan is the only one of the Great Lakes wholly within the borders of the United States; the others are shared with Canada. It has a surface area of 22,400 square miles (58,000 km2), making it the largest lake entirely within one country by surface area (Lake Baikal, in Russia, is larger by water volume), and the fifth largest lake in the world. It is 307 miles (494 km) long by 118 miles (190 km) wide with a shoreline 1,640 miles (2,640 km) long. The lake's average depth is 46 fathoms 3 feet (279 ft; 85 m), while its greatest depth is 153 fathoms 5 feet (923 ft; 281 m).