 Mackinac Island ( / ˈmækᵻnɔː / MAK @-@ in @-@ aw ) is an island and resort area , covering 3 @.@ 8 square miles ( 9 @.@ 8 km2 ) in land area , in the U.S. state of Michigan . It is located in Lake Huron , at the eastern end of the Straits of Mackinac , between the state 's Upper and Lower peninsulas . The island was long inhabited by Native Americans. French fur traders arrived in 1679. Mackinac Island became a center of trade and later a military post. The British acquired the island in 1761, and the Americans took control in 17