Michigan is a Midwestern state in the United States. It is the eighth most populous state in the United States with more than ten million residents. The Metro Detroit area, located in the southeast corner of the state, is the largest metropolitan area in Michigan and one of the ten largest metropolitan areas in the country. Michigan is the leading auto producing state in the U.S. and has the longest freshwater shoreline of any political subdivision in the world, being bounded by four of the five Great Lakes, plus Lake Saint Clair. Michigan is the only state to consist entirely of two peninsulas. The Upper Peninsula is economically important for tourism and natural resources and is separated from the Lower Peninsula by the Straits of Mackinac, a five-mile (8 km)-wide channel that joins Lake Huron to Lake Michigan. The southern and central parts of the Lower Peninsula have a warmer climate with hot summers and cold winters. The northern part of the Lower Peninsula and the entire Upper Peninsula have a more severe climate with warm, but shorter summers and longer, cold to very cold winters.