M-185 is a state trunkline highway in the U.S. state of Michigan that circles Mackinac Island, a popular tourist destination on the Lake Huron side of the Straits of Mackinac, along the island's shoreline. A narrow paved road of 8.004 miles (12.881 km), it offers scenic views of the straits that divide the Upper and the Lower peninsulas of Michigan and Lakes Huron and Michigan. It has no connection to any other Michigan state trunkline highways—as it is on an island—and is accessible only by passenger ferry. The City of Mackinac Island, which shares jurisdiction over the island with the Mackinac Island State Park Commission (MISPC), calls the highway Main Street within the built-up area on the island's southeast quadrant, and Lake Shore Road elsewhere. M-185 passes by several important sites within Mackinac Island State Park, including Fort Mackinac, Arch Rock, British Landing, and Devil's Kitchen. Lake Shore Road carries the highway next to the Lake Huron shoreline, running between the water's edge and woodlands outside of the downtown area.According to the Michigan Department of Transportation (MDOT), M-185 is "the only state highway in the nation where motor vehicles are banned". Traffic on it is by foot, on horse, by horse-drawn vehicle, or by bicycle. Restrictions on automobiles date back to the 1890s, and since the ban, only a few vehicles have been permitted on the island other than the city's emergency vehicles. The highway was built during the first decade of the 20th century by the state and designated as a state highway in 1933. The highway was paved in the 1950s, and portions were rebuilt to deal with shoreline erosion in the 1980s. Until 2005, it was the only state highway without any automobile accidents.