Michigan's unique geographic feature within the United States is that it consists of two peninsulas. Four of the Great Lakes border Michigan, and a 5-mile channel called the Straits of Mackinac divides it into two separate landforms. The state's freshwater shoreline, which is almost 3,300 miles, is the longest in the continental U.S., and Michigan's 96,716-square-mile land area makes it the largest state east of the Mississippi River.
The Upper Peninsula of Michigan is heavily forested. This peninsula's western section is rugged, mountainous and populated by less than 330,000 inhabitants. The Upper Peninsula contains a portion of one of the oldest mountain ranges worldwide called the Porcupine Mountains. The highest point in Michigan is Mount Arvon at 1,979 feet and is part of the Huron Mountains, which are also located on the Upper Peninsula.
The Lower Peninsula accounts for almost two-thirds of Michigan's land area. The land is mostly flat, and broken by glacial moraines and conical hills. Numerous marshes and lakes cover both sections of the state. There are also more than 11,000 inland lakes and 38,575 square miles of Great Lakes waters within the state's borders. Michigan's overall shoreline is heavily indented, and it contains more lighthouses than any other state. There are about 150 lighthouses that were built to help guide the freighters and passenger ships traveling on the four Great Lakes that form the much greater portion of Michigan's borders.