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.[1] There are 977.664 miles (1,573.398 km) of Interstates within the state. The longest is Interstate 15 (I-15) at 400.592 miles (644.690 km) and the shortest is I-215 at 28.946 miles (46.584 km). 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.[2]
I-15 crosses through the entire state, starting in the south from Saint George, up through the middle of the state where it intersects I-70, and into the Salt Lake Valley to meet with I-215 and I-80. After leaving the valley, I-15 continues north, where it becomes concurrent with I-84 until the split in Tremonton, where I-15 heads north into Idaho.[3][4]
Interstate 70 begins in Utah near Cove Fort, not passing through any major metropolitan areas of Utah, and serves as a long-haul route to Denver and the east coast. A stretch of 110 miles (180 km) exists on the highway without any services available.[5][6]
I-84 enters in Snowville and soon becomes concurrent with I-15 until it splits off in Roy, and enters Weber Canyon before ending at I-80 in Echo[10][11]