Interstate 15 in Utah
Interstate 15 runs north–south in the U.S. state of Utah through the southwestern and central portions of the state, passing through most of the state's population centers, including St. George and those comprising the Wasatch Front: Provo–Orem, Salt Lake City, and Ogden–Clearfield. It is Utah's primary and only north–south interstate highway, as the vast majority of the state's population lives along its corridor; the Logan metropolitan area is the state's only Metropolitan Statistical Area through which I-15 does not pass. In 1998, the Utah State Legislature designated Utah's entire portion of the road as the Veterans Memorial Highway.
Route description
The Interstate passes through the fast-growing Dixie region, which includes St. George and Cedar City, and eventually most of the major cities and suburbs along the Wasatch Front, including Provo, Orem, Sandy, West Jordan, Salt Lake City, Layton, and Ogden. Around Cove Fort, I-70 begins its journey eastward across the country. The Interstate merges with I-80 for about from South Salt Lake to just west of Downtown Salt Lake City and merges with I-84 from Ogden to Tremonton. Along nearly its entire length through the state, I-15 winds its way along the western edge of a nearly continuous range of mountains. The only exceptions are when it passes through the mountains south of Cedar City and, again, north of Cove Fort.Southern Utah
From Las Vegas, Nevada, I-15 winds and slightly inclines through the Virgin River Gorge in northwest Arizona, then it crosses the border into Utah and Washington County. Just past the border, there is a port of entry on each side of the freeway. These ports of entry are jointly operated by the states of Utah and Arizona and are the first northbound exit and last southbound exit on I-15 in Utah. Heading north-northeast, it continues with two lanes in each direction until it reaches an interchange with Southern Parkway, which provides access to the St. George Regional Airport. After SR-7, the route turns north as it passes the Bloomington area of the City of St. George and an interchange at Brigham Road, where an auxiliary lane is added before it crosses the Virgin River. This marks the lowest elevation along I-15 in Utah, above sea level. Immediately north of the Virgin River and partially spanning the Santa Clara River, is the Dixie Drive interchange. A collector ramp is added between Dixie Drive and the next interchange with Bluff Street. I-15 then narrows to two lanes in each direction and turns northeast again, where it passes the eastern side of downtown St. George, with an interchange at St. George Boulevard. The Bluff Street and St. George Boulevard interchanges are the southern and northern ends of the St. George I-15 Business Loop. From this point north, I-15 generally follows the route of the Old US 91, maintaining a two-lane configuration until it reaches the Wasatch Front in the north-central part of the state.After leaving St. George, I-15 continues northeast and passes through the northern part of the city of Washington. An auxiliary lane is added between St. George Boulevard and Green Springs Road with additional interchanges at Washington Parkway and State Street. Northeast of Washington, I-15 passes through the northwestern side of the town of Leeds, with one-way interchanges on the southwest and northeast ends of town. After passing through the northwestern part of Toquerville, and an interchange with SR-17, I-15 resumes a more north-northeastern course as it ascends about higher on the Colorado Plateau. Along the way, it passes through the areas of Browse and Pintura, with interchanges at both, as well as two more ranch exits further northeast. After its ascent, it passes by the east of side of Ash Creek Reservoir and then by the northwest corner of Zion National Park, with an interchange providing access to the Kolob Canyon area of the park. Next is an interchange that provides access to New Harmony and Kanarraville. This interchange is also at the border of Washington County and Iron County.
Just after entering Iron County, I-15 reaches the southernmost rest areas along its route within the state. After passing about a mile west of Kanarraville, it reaches an interchange in Hamilton Fort. The freeway then briefly turns nearly east before turning north again to pass through the west side of Cedar City. The first interchange is at the southern end of SR-130 and the Cedar City I-15 Business Loop. Just north is the 200 South interchange, which provides access to downtown Cedar City as well as the Cedar City Regional Airport. After this interchange, the freeway turns northeast before the final Cedar City interchange with SR-130. This interchange is also the northern end of the Cedar City I-15 Business Loop, although no longer indicated as such by signage. The freeway then passes by the eastern edge of Enoch, but without an interchange within that city. After an interchange within the area of Summit, I-15 heads east-northeast before passing by the northwest edge of Parowan, with interchanges on the west and north sides of town. After Parowan, the freeway curves back to a northeast course as it passes about a mile west of Paragonah and reaches an interchange on the north side of that city. Continuing northeast, it reaches the next pair of rest areas before an interchange with SR-20 and then a ranch exit before leaving Iron County.
Central Utah
As I-15 enters Beaver County, the Interstate turns northwestward and winds its way through the mountain pass before heading north again to pass along the western edge of the city of Beaver. The southern and northern interchanges in Beaver include the I-15 Business Loop and SR-160—the city streets are South Main Street on the south and 1400 North on the north. Off the 1400 North interchange, there is an official rest stop, courtesy of Utah Department of Transportation and the local Texaco Station. The freeway then heads slightly westward until it passes by the western side of the community of Manderfield and curves back to a north-northeast course. After several miles, there is an interchange with Manderfield Road before I-15 winds through another mountain pass and reaches the Sulphurdale interchange. This mountain pass, with a summit located at milepost 124.8, is the highest point along I-15 in Utah, at above sea level. After passing west of the ghost town of Sulphurdale, it reaches the interchange with the western end of I-70. This interchange is on the border of Beaver and Millard counties.North of the I-15/I-70 interchange, I-70 heads east to Richfield and then toward Denver, Colorado, while I-15 continues north to pass by Cove Fort on the east and reach the Cove Fort interchange. Off the Black Rock Road interchange is an official rest stop, courtesy of UDOT and the local Chevron Station. I-15 meanders to the north-northeast before straightening out to the northeast–southwest of Kanosh. The freeway passes by the northwestern side of Meadow, having an interchange with North Main Street. It then passes through the western side of Fillmore. SR-99 follows the length of the I-15 Business Loop through Fillmore, connecting at 850 South on the southwestern part of town and North Main Street / Cedar Mountain Road on the northern city limits. Off the North Main Street interchange, there is an official rest stop courtesy of UDOT and the local Chevron Station. Continuing north-northwest, it has an interchange with 5400 North / Maple Hollow Road before passing by the southeast edge of Holden. Several miles northeast of Holden, US 50 merges with I-15 as it continues northeastward and eventually heading through a low mountain pass just after another ranch exit. The US 50 overlap then ends as I-15 passes through the northwestern corner of Scipio. Off the Scipio interchange, is an official rest stop courtesy of UDOT and Flying J.
Several miles north of Scipio, I-15 leaves Millard County and enters Juab County before turning northeastward again. After an interchange with the Yuba Lake Road is another interchange at Mills Junction / SR-78 just southeast of Chicken Creek Reservoir. The freeway then continues roughly north-northeast until it turns northeast to pass through the southern part of Nephi and an interchange with South Main Street. The freeway then turns north to pass through the eastern side of Nephi, with an interchange with 100 North. It then curves to the north-northwest before reaching the interchange with the northern end of SR-28 about a mile north of town. The Interstate then turns north and passes by the eastern side of Mona and has an interchange with SR-52. Continuing north, it passes by the eastern edge of Rocky Ridge before promptly leaving Juab County and entering Utah County.
Northern Utah
Salt Lake area
As the freeway enters Utah County, it also enters Utah Valley, the Wasatch Front, and the Provo–Orem metropolitan area. Turning northeast, it enters the town of Santaquin, where US 6 begins its overlap with I-15 at the interchange with East Main Street / US 6 / SR-198. Exiting Santaquin, the Interstate turns north to pass by the western edge of Spring Lake before entering Payson, turning northeast, and reaching the 800 South interchange. Continuing northeast, the freeway reaches the interchange with North Main Street in north Payson. Maintaining its course to the northeast, it passes the eastern edge of Benjamin, with an interchange with SR-164, and enters Spanish Fork and gains one lane in each direction. On the north side of Spanish Fork is an interchange with North Main Street, after which I-15 turns north and gains one more lane in each direction. This interchange also marks the northern end of the overlap with US 6.File:2015-09-29 13 56 14 View north along Interstate 15 and west along Interstate 80 looking towards Salt Lake City, Utah from South Salt Lake, Utah.jpg|thumb|right|View north along I-15 at the southern junction with I-80 and SR-201 in Salt Lake County
Continuing north with four lanes, it gains an additional express lane in both directions. It then passes through the far west side of Springville, with interchanges at 400 South and 1400 North. Off the 1400 North interchange is an official rest stop courtesy of UDOT and Flying J. Curving northwest, it passes the eastern edge of the Provo Bay of Utah Lake before reaching Provo. Upon entering Provo, it intersects with South University Avenue and East Lakeview Parkway. The Interstate then continues northwest, bisecting the west side of Provo, with an interchange with Center Street before leaving Provo and entering Orem. After an interchange with West University Parkway, immediately southwest of Utah Valley University, the freeway heads north along the western side of Orem. After interchanges with Center Street, and then 800 North, the Interstate curves northwest and immediately reaches the interchange with SR-241. This interchange on the border of Orem and Lindon.
Continuing northwest, I-15 passes through the western side of Lindon before passing by the southwest edge of Pleasant Grove, with an interchange at Pleasant Grove Boulevard. Next, the freeway enters American Fork with interchanges at 500 East on the south end of town and West Main Street / Pioneer Crossing on the west end of town. After American Fork, the freeway enters Lehi with its first interchange at East Main Street. At this point, the Interstate narrows to three lanes in each direction. The next interchange in Lehi is with 2100 North / 1200 West. This also begins the first of two I-15 / US 89 overlaps. The final interchange in Lehi is with Timpanogos Highway / Clubhouse Drive, after which the Interstate gains an additional two lanes, which is just east of Thanksgiving Point. Past Lehi, the Interstate exits the Provo metropolitan area and Utah County to enter the Salt Lake City metropolitan area as it passes through the Point of the Mountain.
As the route enters the Salt Lake Valley from only one of three other points connecting Salt Lake County and Utah County, it turns northeast to pass by the eastern edge of Bluffdale. It then enters Draper and heads north to pass through the western part of that city, with four interchanges along the way. The first is with Highland Drive / 14600 South. The next interchange is with Bangerter Highway. The third interchange in Draper is with 12300 South. This interchange is also where US 89 ends its first overlap with the Interstate and where I-15 curves slightly to the west. The final interchange in town is on the northern city limits at 11400 South. This interchange is on the southern border of Sandy, and is the first of three within that city. The next interchange is with 10600 South. The final interchange in Sandy is with 9000 South.
Shortly after the last interchange in Sandy, it leaves that city and enters Midvale, with the only interchange in that city being with 7200 South. After leaving Midvale, I-15 enters Murray and immediately reaches the junction with I-215, a beltway running through many of Salt Lake City's suburbs. Past this interchange, there are two more interchanges in Murray. The first is at 5400 South and the second is with 4500 South / Taylorsville Expressway. After this interchange, the freeway leaves Murray and passes through the western end of Millcreek before entering South Salt Lake. After an interchange with 3300 South, the Interstate reaches the Spaghetti Bowl, which is an interchange with I-80 and SR-201. The southern overlap of I-80 begins at this point as well as the collector roads. The collectors, but not the main I-15 travel lanes, have interchanges with 2100 South and 1300 South, as well as West Temple Street for northbound traffic only. The Spaghetti Bowl is also where the freeway leaves South Salt Lake enters Salt Lake City.
After entering Salt Lake City, the Interstate jogs to the west for the next three interchanges. The first is with SR-269 and includes the offramps from northbound I-15/I-80 to eastbound 600 South and the onramps from westbound 500 South to southbound I-15/I-80. The next two interchanges are overlain and include I-80 and 400 South. North of the ramps with I-80, I-15 loses one lane, leaving three lanes, plus the express lane, in both directions. The next interchange is with 600 North, following which the freeway jogs to the west for the next two interchanges. After the 900 West interchange is the Warm Springs Road and 2300 North interchange. The freeway then returns to is northern course, but before leaving Salt Lake City and Salt Lake County, it has northbound on- and offramps for the Beck Street interchange.