The Interstate Highways in Michigan are the segments of the national Dwight D. Eisenhower System of Interstate and Defense Highways that are owned and maintained by the U.S. state of Michigan, totaling about 1,239 miles (1,994 km). On a national level, the standards and numbering for the system are handled by the Federal Highway Administration and the American Association of State Highway and Transportation Officials, while the highways in Michigan are maintained by the Michigan Department of Transportation and the Mackinac Bridge Authority. These highways have their origins in World War II-era expressways built in the Detroit area before the 1956 creation of the Interstate Highway System. The last highway was completed in 1992, giving Michigan a total of 13 Interstate freeways. There are also 26 current and six former business routes associated with the system in the state and one planned, but unbuilt, freeway.
