The Upper Peninsula (U.P.) is the northern of the two major peninsulas that make up the U.S. state of Michigan. It may also be referred to as Upper Michigan, and is known colloquially as "the land above the Bridge", referring to the Mackinac Bridge linking it with Lower Michigan. The peninsula is bounded on the north by Lake Superior, on the east by the St. Marys River, on the southeast by Lake Michigan and Lake Huron, and on the southwest by Wisconsin.