List of Interstate Highways in Utah
The Interstate Highways in Utah are maintained by the Utah Department of Transportation (UDOT). The Interstate Highway System is a nationwide system with only a small portion of these routes entering Utah. Originally, the State Road Commission of Utah, created on March 23, 1909 was responsible for maintenance, but these duties were rolled into the new UDOT in 1975. There are of Interstates within the state. The longest is Interstate 15 (I-15) at and the shortest is I-215 at . One unique former route is Interstate 415, which was never signed as such, and was only used as a temporary designation for the eastern portion of what is now the Interstate 215 belt loop around Salt Lake City.
List of Interstate Highways in Michigan
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 . The longest of these, Interstate 75 (I-75), is also the longest highway of any kind in the state. On a national level, the standards and numbering for the system are handled by the Federal Highway Administration (FHWA) and the American Association of State Highway and Transportation Officials (AASHTO), while the highways in Michigan are maintained by the Michigan Department of Transportation (MDOT) and the Mackinac Bridge Authority (MBA). The Interstates in Michigan have their origins in World War II-era expressways built in the Detroit area. After the system was created in 1956, the state highway department completed its first border-to-border Interstate in 1960. The last highway was completed in 1992, giving Michigan a total of 13 Interstate freeways. The original allotment of mileage to Michigan which would receive federal funding was expanded in 1968, and the United States Congress designated an additional highway in the 1990s that has not yet been built.