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.
Alaska
Alaska has few road connections compared to the rest of the U.S. The state's road system covers a relatively small area of the state, linking the central population centers and the Alaska Highway, the principal route out of the state through Canada. The state capital, Juneau, is not accessible by road, only a car ferry, which has spurred several debates over the decades about moving the capital to a city on the road system, or building a road connection from Haines. The western part of Alaska has no road system connecting the communities with the rest of Alaska.
The Interstate Highways in Alaska consists of a total of 1082 miles. One unique feature of the Alaska Highway system is the Anton Anderson Memorial Tunnel, an active Alaska Railroad tunnel recently upgraded to provide a paved roadway link with the isolated community of Whittier on Prince William Sound to the Seward Highway about southeast of Anchorage at Portage. At , the tunnel was the longest road tunnel in North America until 2007. The tunnel is the longest combination road and rail tunnel in North America.