This island, located in the United States, is situated at the junction of two of North America's Great Lakes. It covers an area of approximately 4.35 square miles and is known for its limestone cliffs and Arch Rock. The island is famous for banning motor vehicles, with transportation being done via horses, buggies, and bicycles. It also retains an 18th- and 19th-century atmosphere with historical sites like Fort Mackinac and Beaumont Memorial. Which island is being described?