Interstate 15 is the most important north-south corridor in Utah, passing through the heart of the Beehive State. Originating at the north end of the Virgin River Gorge, Interstate 15 immediately enters St. George, then proceeds north to Cedar City, Beaver, Cove Fort, Nephi, Santaquin, Spanish Fork, Provo, Orem, Sandy City, Salt Lake City, Ogden, Brigham City, and Tremonton. The freeway serves the great Salt Lake City metropolitan area by connecting the capital city with Provo to the south and Ogden to the north. The freeway stays along the western reaches of the Wasatch Mountain Range from southwest Utah through to Great Salt Lake.
Interstate 15 Utah Highway Guides
- Interstate 15 North - Washington County (St. George)
- Interstate 15 North - Iron County (Cedar City)
- Interstate 15 North - Beaver and Millard Counties
- Interstate 15 North - Juab County
- Interstate 15 North - Utah County (Provo)
- Interstate 15 North - Salt Lake County
- Interstate 15 North - Davis, Weber, and Box Elder Counties
- Interstate 15 Archive - North
- Interstate 15 South - Box Elder County
- Interstate 15 South - Weber and Davis Counties
- Interstate 15 South - Salt Lake City to Murray
- Interstate 15 South - Midvale to Bluffdale
- Interstate 15 South - Utah County (Provo)
- Interstate 15 South - Juab County
- Interstate 15 South - Millard and Beaver Counties
- Interstate 15 South - Iron County (Cedar City)
- Interstate 15 South - Washington County (St. George)
- Interstate 15 Archive - South
Between St. George and Spanish Fork, Interstate 15 largely replaced U.S. 91. Segments of the historic highway are still in use as business routes and state highways. Between Spanish Fork and Brigham City, Interstate 15 parallels U.S. 89 and Old U.S. 91, with several segments of U.S. 89 still in use. North of Brigham City, Interstate 15 replaced Historic U.S. 191. Once Interstate 15 replaced U.S. 191, that designation was available to be relocated elsewhere (and in 1981, it was relocated into western Wyoming and eastern Utah).
Just three sections of Interstate 15 were open to traffic by 1969. They included 8.8 miles from North cedar City to Summit, 6.2 miles from south Beaver to north Beaver, and 9.8 miles from 31st Street in Ogden to Hot Springs. Another 31.1 miles of the freeway were under construction in 1969. This included portions north of Cedar City and between Ogden and Brigham City.1
268.88 miles of I-15 in the Beehive State were open to traffic by 1974. Construction schedules then extended to 1983, with the 6.9 mile segment between the Sevier River and Mills Junction the projected last in line.2
Concerns from local leaders and citizens however led to a number of hearings on the final proposals for Interstate 15, delaying completion of the route until November 20, 1990. Hearings focused on potential impacts to prime agricultural land, related effects on local tax bases and the exact route I-15 would follow. Costing $37 million, the final 26 mile section, last of the Utah Interstate system to be built, opened following a formal ceremony in Riverside.3
Interstate 15 Business Routes
- St. George - follows Utah 18 and Utah 34
- Cedar City - follows Utah 130
- Parowan - follows Utah 274
- Beaver - follows Utah 160
- Fillmore - follows Utah 99
- Nephi - follows Utah 28 (former Utah 41)
- Brigham City - follows U.S. 91 and U.S. 89-91
- Tremonton - follows Utah 102 and Utah 13
- Decommissioned Business Routes: Holden and Layton
|Interstate 15 scenes|
|Interstate 15 shields posted at the ranch exit west of old U.S. 91 and Sulphurdale. This assembly was removed by 2014. Photo taken 10/18/04.|
|Sign replacement for Interstate 15 at Exit 129, west of the Tushar Mountains. Utah, like the state of Wyoming, places wooden shields and signs along their roadways. Photo taken 10/18/04.|
|A new guide sign installed for the northbound on-ramp to I-15 from the ranch exit near Sulphurdale. Old U.S. 91 parallels the freeway just to the east from here. Photo taken 10/18/04.|
|Westbound Utah 209 (9000 South) approaches the SPUI with Interstate 15 in the city of Sandy. I-15 constitutes a busy commuter freeway north to Salt Lake City and south to Orem and Provo. Photo taken 05/16/12.|
|A new guide sign installed for the northbound on-ramp to I-15 from the ranch exit near Sulphurdaale. Old U.S. 91 parallels the freeway just to the east from here. Photo taken 01/21/11.|
- "105 Miles Planned For Utah's Interstate." The Deseret News, January 11, 1969.
- "Rough going for interstate." The Deseret News, May 16, 1974.
- "Wintry slush fails to dampen spirits at opening of last stretch of interstate." The Deseret News, November 21, 1990.
- 10/18/04 by AARoads.
- 01/21/11 by Garrett Smith.
- 05/16/12 by Steve Hanudel and Erik Slotboom.
Page Updated 08-04-2016.