Montreal River (Wisconsin–Michigan) in the context of "Upper Peninsula of Michigan"

The Upper Peninsula of Michigan—also known as Upper Michigan or colloquially the U.P. or Yoop—is the northern and more elevated of the two major landmasses that make up the U.S. state of Michigan; it is separated from the Lower Peninsula by the Straits of Mackinac. It is bounded primarily by Lake Superior to the north, separated from the Canadian province of Ontario at the east end by the St. Marys River, and flanked by Lake Huron and Lake Michigan along much of its south. Although the peninsula as a geographic feature extends into the state of Wisconsin, the state boundary follows the Montreal and Menominee rivers and a line connecting them.

First inhabited by Algonquian-speaking native American tribes, the area was explored by French colonists, then occupied by British forces, before being ceded to the newly established United States in the late 18th century. After being assigned to various territorial jurisdictions, it was granted to the newly formed state of Michigan as part of the settlement of a dispute with Ohio over the city of Toledo. The region's exploitable timber resources and the discovery of iron and copper deposits in the 19th century brought immigrants, especially Finnish, French Canadian, Swedish, Norwegian, Cornish, and Italian; the peninsula includes the only counties in the United States where a plurality of residents claim Finnish ancestry. The area's economy declined in the 20th century when all of the readily available minerals had been removed, and it became largely dependent on logging and tourism.