Arch Rock is a natural limestone arch on Mackinac Island above the Lake Huron shoreline, formed during the Nipissing post-glacial period when lake levels were higher after the Wisconsin glaciation. Rising about 146 feet above the water, it is an uncommon Great Lakes formation and one of the island’s best-known geological landmarks. Long before becoming a tourist attraction, it held spiritual importance for Native Americans and was associated with stories and legends. By the 19th century, visitors such as Alexis de Tocqueville admired it as a scenic wonder. Its prominence helped inspire the creation of Mackinac National Park in 1875 and Mackinac Island State Park in 1895.