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.
Special routes of U.S. Route 95
The route now known as US 95 Spur was previously known as US 630 and US 30N. US 630 was an east–west United States highway. It was decommissioned in or around 1931. With a length of around , it was the shortest US route ever signed. It was concurrent with US 30N for its entire length. An earlier route numbered US-630 was proposed from Echo, Utah (northeast of Coalville) to Ogden, Utah, but was never signed in the field. U.S. Route 30N was a split route off of US-30 and was coterminous with US 630 at its west end in Oregon. East of Weiser, it was concurrent with what is now US-95 to Fruitland, Idaho, where it reconnected with US-30.