Mackinaw Island

The only state highway in the U.S. that prohibits motorized vehicles is M-185 on Mackinaw Island in Michigan.

The island can be reached by private boat, by ferry, by small aircraft, and in the winter, by snowmobile over an ice road.

The airport has a 3,500-foot (1,070 m) paved runway, and daily charter air service from the mainland is available. 

In the summer tourist season, ferry service is available from Arnold Transit Company, Shepler's Ferry, and Star Line Ferry to shuttle visitors to the island from St. Ignace and Mackinaw City.

Motorized vehicles have been prohibited on the island since 1898 with the exception of snowmobiles during winter, emergency vehicles, and service vehicles.