The Michigan Department of Transportation (MDOT) says that the 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. Cars have been banned on the island since the 1890s. Only a few vehicles have been allowed 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. It was designated as a state highway in 1933. The highway was paved in the 1950s. Parts were rebuilt to deal with coastal erosion in the 1980s. Until an accident in 2005, it was the only state highway without any car accidents.