Editing Interstate 15

{{Short description|Interstate in the Western United States}}
{{Use American English|date=April 2025}}
{{Use mdy dates|date=March 2017}}
{{Infobox road
|country=USA
|type=I
|route=15
|map={{maplink|frame=yes|plain=yes|frame-align=center|frame-width=290|frame-height=290|type=line|from=Interstate 15.map}}
|map_custom=yes
|map_notes=I-15 highlighted in red
|length_mi=1433.52
|length_round=2
|length_ref=<ref name="USDOT">{{cite web |url = https://www.fhwa.dot.gov/planning/national_highway_system/interstate_highway_system/routefinder/?redirect |title = Table 1: Main Routes of the Dwight D. Eisenhower National System of Interstate and Defense Highways as of October 31, 2002 |date = October 31, 2002 |publisher = [[Federal Highway Administration]] |access-date = July 20, 2011 |archive-date = May 27, 2012 |archive-url = https://archive.today/20120527023005/http://www.fhwa.dot.gov/reports/routefinder/table1.htm |url-status = live }}</ref>
|established=1957
|direction_a=South
|terminus_a={{jct|country=USA|state=CA|I|8|SR|15|nolink2=yes}} in [[San Diego|San Diego, CA]]
|junction=<!-- Major Interstate junctions only; Only 5-8 most major intersections and cities belong here; please read [[WP:USRD/STDS]] for more info -->
*{{jct|country=USA|I|10}} in [[Ontario, California|Ontario, CA]]
*{{jct|country=USA|I|40}} in [[Barstow, California|Barstow, CA]]
*{{jct|country=USA|I|11|US|93|US|95}} in [[Las Vegas, Nevada|Las Vegas, NV]]
*{{jct|country=USA|I|70}} near [[Cove Fort, Utah|Cove Fort, UT]]
*{{jct|country=USA|I|80}} in [[Salt Lake City|Salt Lake City, UT]]
*{{jct|country=USA|I|84|dab1=Oregon-Utah}} from [[Riverdale, Utah|Riverdale, UT]] to [[Tremonton, Utah|Tremonton, UT]]
*{{jct|country=USA|I|86|dab1=Idaho}} in [[Chubbuck, Idaho|Chubbuck, ID]]
*{{jct|country=USA|I|90}} near [[Butte, Montana|Butte, MT]]
|direction_b=North
|terminus_b={{Jct|province=AB|Hwy|4}} at [[Sweetgrass–Coutts Border Crossing]] at [[Sweet Grass, Montana|Sweet Grass, MT]]
|states=[[California]], [[Nevada]], [[Arizona]], [[Utah]], [[Idaho]], [[Montana]]
}}

'''Interstate&nbsp;15''' ('''I-15''') is a major [[Interstate Highway System|Interstate Highway]] in the [[Western United States]], running through [[Southern California]] and the [[Intermountain West]]. I-15 begins near the [[Mexico–United States border|Mexican border]] in [[San Diego County, California|San Diego County]] and stretches north to [[Alberta|Alberta, Canada]], passing through the states of [[California]], [[Nevada]], [[Arizona]], [[Utah]], [[Idaho]], and [[Montana]]. The Interstate serves the cities of [[San Diego]], [[San Bernardino]], [[Las Vegas]], [[Salt Lake City]], [[Idaho Falls, Idaho|Idaho Falls]], and [[Great Falls, Montana|Great Falls]]. It also passes close to the urban areas of [[Los Angeles County|Los Angeles]], [[Orange County, California|Orange]], and [[Riverside County|Riverside]] counties in California. The stretches of I-15 in Idaho,{{cn|date=October 2024}} Utah, and Arizona have been designated as the "Veterans Memorial Highway".<ref>{{cite web | last=Trishman | first=Robert | title=I-15 rededicated as Veterans Memorial Highway | website=Deseret News | date=February 10, 2012 | url=https://www.deseret.com/2012/2/10/20392593/i-15-rededicated-as-veterans-memorial-highway/ | access-date=October 26, 2024}}</ref><ref>{{cite web | title=Arizona highways honor veterans all year long | website=Department of Transportation | date=November 10, 2016 | url=https://azdot.gov/blog-article/arizona-highways-honor-veterans-all-year-long | access-date=October 26, 2024}}</ref> The southern end is at a junction with [[Interstate 8|I-8]] and [[Interstate 15 in California|State Route&nbsp;15]] (SR&nbsp;15) in San Diego, and the northern end is at a connection with [[Alberta Highway 4]] at the [[Sweetgrass–Coutts Border Crossing]].

I-15 was built to connect the [[Inland Empire]] with San Diego in California, facilitate tourism access to Las Vegas, provide access to the [[Arizona Strip]], interconnect all of the [[metropolitan statistical area]]s in Utah except for [[Logan, Utah|Logan]], and provide freeway bypasses for [[Pocatello, Idaho|Pocatello]], Idaho Falls, and Great Falls. Since its creation, I-15 has served as a long-haul route for [[North America]]n commerce. It is now officially chartered for this purpose: from the junction of [[Interstate 11|I-11]] in [[Las Vegas]] to the [[Canada–United States border|Canadian border]], I-15 forms part of the [[CANAMEX Corridor]], a [[Intermodal Surface Transportation Efficiency Act|High Priority Corridor]], as a result of the [[North American Free Trade Agreement]].<ref name=canamex>{{cite web |url = http://www.canamex.org/ |title = CANAMEX CORRIDOR, The safe, smart and secure corridor |access-date = January 2, 2008 |publisher = Canamex Corridor Project |archive-url = https://web.archive.org/web/20080101020328/http://www.canamex.org/ |archive-date = January 1, 2008 |url-status = dead }}</ref> Since the construction of I-15, California, Idaho, Nevada, and Utah have consistently ranked in the fastest-growing areas of the United States. As a result, the route of I-15 has substantially increased in population and commuter traffic.

==Route description==
{{lengths table|length_ref=<ref name="USDOT"/>}}
|-
|[[Interstate 15 in California|CA]]
|{{convert|287.26|mi|km|disp=table}}
|-
|[[Interstate 15 in Nevada|NV]]
|{{convert|123.77|mi|km|disp=table}}
|-
|[[Interstate 15 in Arizona|AZ]]
|{{convert|29.39|mi|km|disp=table}}
|-
|[[Interstate 15 in Utah|UT]]
|{{convert|401.07|mi|km|disp=table}}
|-
|[[Interstate 15 in Idaho|ID]]
|{{convert|196.00|mi|km|disp=table}}
|-
|[[Interstate 15 in Montana|MT]]
|{{convert|396.03|mi|km|disp=table}}
|-
|Total
|{{convert|1433.52|mi|km|disp=table}}
|}
{{multiple image
| direction         = vertical
| width             = 250
| image1            = Interstate15 Ivanpah Valley.jpg
| caption1          = Northbound I-15 makes a steep descent from the Mountain Pass into the [[Ivanpah Valley]]
| image2            = Interstate_15,_Las_Vegas,_South_of_Flight_Path_on_Departure_(14203692275).jpg
| caption2          = Aerial view of I-15 looking south from Sunset Road in the [[Las Vegas Valley]]
| image3            = Red rock cliff walls in Virgin River Gorge.jpg
| caption3          = I-15 passes through the [[Virgin River]] Gorge, Arizona, revealing scenic reddish brown cliffs
| image4            = Interstate 15 Arizona.jpg
| caption4          = I-15 in Arizona
| image5            = I-15indowntown.jpg
| caption5          = I-15 in [[Salt Lake City]]
| image6            = I 15 US 20 Junction Sign.jpg
| caption6          = I-15/US&nbsp;20 Jct. in [[Idaho Falls, Idaho]]
| image7            = Interstate15ruralMT.jpg
| caption7          = I-15, {{Convert|20|mi|km}} south of [[Dillon, Montana]]
| image8            = greatfallscitylights.jpg
| caption8          = I-15 (foreground left to right) goes through [[Great Falls, Montana]]
}}

This highway's southern terminus is in [[San Diego|San Diego, California]], at [[Interstate 8|I-8]], although via [[California State Route 15|SR&nbsp;15]], a southern extension of the freeway, the route connects to [[Interstate 5|I-5]] 12.5 miles from the US/Mexico border in southern San Diego.<ref name=sr15reconstruction>{{cite book |publisher = [[California Department of Transportation]] |date = December 2010 |title = State Route 15: Mid-City Bus Rapid Transit Project |page = 1 }}</ref> The northern terminus is in [[Sweet Grass, Montana]], at the Canada–US border, where it becomes [[Alberta Highway 4]]. It is {{convert|1433|mi|km|0}} long from San Diego to Sweet Grass.

===California===
{{Main|Interstate 15 in California}}

North of its junction with [[California State Route 91|SR&nbsp;91]] in [[Corona, California|Corona]], the route roughly follows the former routes of State Route 31. North of [[Devore, California|Devore]], the highway follows the approximate alignment of historic [[U.S. Route 66|US Route&nbsp;66]] along with [[U.S. Route 91|US&nbsp;91]] and [[U.S. Route 395|US&nbsp;395]]. US&nbsp;395 breaks away at Hesperia and the route continues on a direct path to [[Barstow, California|Barstow]] {{convert|35|mi|km|0}} to the north. Meanwhile, the old alignments of US&nbsp;91 and US&nbsp;66 follow the [[Mojave River]] from [[Victorville, California|Victorville]] to Barstow along the [[National Old Trails Road|National Trails Highway]]. At that point, I-15 follows the old route of US&nbsp;91 exclusively as US&nbsp;66 turned east toward [[Needles, California|Needles]]. For many parts of the highway, high-voltage [[electric power transmission|powerline]]s, such as [[Path 46]] and [[Path 27]], almost all originating from the [[Hoover Dam]], follow the freeway. Many of these link distant power stations to the [[Los Angeles]] metropolitan area.

The southern starting point of I-15 was in 1957 planned to be in [[San Bernardino, California|San Bernardino]], at the interchange with the San Bernardino Freeway (then US&nbsp;70/US&nbsp;99, now [[Interstate 10|I-10]]). This was logical as I-15 was following the old alignment of the historic Route&nbsp;66 which passed through San Bernardino. The segment was completed accordingly.

In 1964, legislation was later passed to extend the Interstate to [[San Diego]]. Instead of extending the existing freeway from the I-10 interchange south, however, the [[California Department of Transportation]] drew a new segment in Devore that "branched" off of the original alignment and bypassed San Bernardino altogether. This segment's alignment is generally northeast to southwest for about {{convert|13|mi|km|0}}. Then, in [[Rancho Cucamonga, California|Rancho Cucamonga]], its directional alignment shifts to north–south where it eventually meets with I-10 (about {{convert|15|mi|km}} west of the original interchange in San Bernardino). The segment that had been built from Devore to San Bernardino was retained as an Interstate, but was renumbered as [[Interstate 215 (California)|I-215]]. Note that during the construction of I-15's present alignment, and for some time afterward, I-215 was numbered as I-15E, and its actual mileage would begin at I-10. I-15 runs for a total of {{convert|287|mi|km|0}} in California.

===Nevada===
{{Main|Interstate 15 in Nevada}}

I-15 begins in [[Primm, Nevada|Primm]] and continues through [[Las Vegas]] along the [[Las Vegas Strip]] corridor. Then, the Interstate crosses the border with [[Arizona]] in [[Mesquite, Nevada|Mesquite]]. The Interstate in [[Nevada]] runs entirely in [[Clark County, Nevada|Clark County]], for a distance of {{convert|123.8|mi|km|0}}.

===Arizona===
{{Main|Interstate 15 in Arizona}}

I-15 passes through the [[Arizona Strip|northwestern corner]] of [[Arizona]] with a total length of {{convert|29.4|mi|km|0}}.<ref>Arizona Department of Transportation Project 015 MO 000 H577901C, sheet 73 of 103 - revised May 2005</ref> The stretch is separated from the rest of the state and has one major exit, at [[Beaver Dam, Arizona|Beaver Dam]]/[[Littlefield, Arizona]]. It includes a spectacular section where the road twists between the narrow walls of the [[Virgin River Gorge]].

===Utah===
{{Main|Interstate 15 in Utah}}

I-15 continues through [[Utah]] for {{convert|401|mi|km|0}}. It is the main north–south connection for the state. The highway approximately follows the old alignment of [[U.S. Route 91|US&nbsp;91]] from [[St. George, Utah|St. George]] to [[Brigham City, Utah|Brigham City]]. The highway passes through the fast-growing [[Utah's Dixie]] region in the southwestern part of the state, which includes [[St. George, Utah|St. George]], [[Cedar City, Utah|Cedar City]], and eventually most of the major cities and suburbs along the [[Wasatch Front]], including [[Provo, Utah|Provo]], [[Orem, Utah|Orem]], [[Sandy, Utah|Sandy]], [[Salt Lake City]], [[Layton, Utah|Layton]], and [[Ogden, Utah|Ogden]]. Near [[Cove Fort, Utah|Cove Fort]], [[Interstate 70 in Utah|I-70]] begins its journey eastward across the country. The Interstate [[Concurrency (road)|merges]] with [[Interstate 80 in Utah|I-80]] for about {{convert|3|mi|km|0}} from [[South Salt Lake, Utah|South Salt Lake]] to just west of [[Downtown Salt Lake City]] and also merges with [[Interstate 84 in Utah|I-84]] from [[Ogden, Utah|Ogden]] to [[Tremonton, Utah|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 [[Wasatch Range]] in the northern half of the state). The only exceptions are north of [[Cove Fort, Utah|Cove Fort]] and when it passes between [[Cedar City, Utah|Cedar City]] and St. George, known as the Black Ridge, a transition zone of drastic change in elevation and climate, an area where the eastern [[Great Basin]], [[Colorado Plateau]], and [[Mojave Desert]] converge.

===Idaho===
{{Main|Interstate 15 in Idaho}}

I-15 passes through [[Idaho]] for {{convert|196|mi|km|0}}. I-15 crosses the [[Utah]] state line in [[Oneida County, Idaho|Oneida County]]. The highway runs through [[Pocatello, Idaho|Pocatello]], [[Blackfoot, Idaho|Blackfoot]], and [[Idaho Falls, Idaho|Idaho Falls]], intersecting with [[Interstate 86 (west)|I-86]]. The last county in Idaho that I-15 passes through is [[Clark County, Idaho|Clark County]]. Finally, the Interstate reaches the [[Montana]] state line at [[Monida Pass]].

===Montana===
{{Main|Interstate 15 in Montana}}
I-15 continues onward through {{convert|396|mi|km|0}} of [[Montana]] through the cities of [[Butte, Montana|Butte]], [[Helena, Montana|Helena]], and [[Great Falls, Montana|Great Falls]], intersecting with [[Interstate 90 in Montana|I-90]], [[I-115]], and [[I-315]]. At [[Sweet Grass, Montana|Sweet Grass]], I-15 terminates upon [[Sweetgrass–Coutts Border Crossing|crossing the Canadian border]] into the province of [[Alberta]]; however, I-15 signage is present on [[Alberta Highway 4]] southbound from [[Lethbridge]] to the [[Canada–United States border|Canadian border]].

==History==
I-15 was constructed along the route of [[U.S. Route 91|US&nbsp;91]]. Once I-15 was relatively intact, US&nbsp;91 was decommissioned, except for one part in Northern Utah&nbsp;/ Southern Idaho where I-15 instead followed the route of former [[U.S. Route 191|US&nbsp;191]].

I-15 originally had two suffixed routes. In California, I-15 had an eastern branch bypassing [[San Bernardino, California|San Bernardino]], which was designated I-15E. I-15E was renumbered and is now [[Interstate 215 (California)|I-215]]. Present day routing of I-15 in California was originally given "I-15W" as its title while it was under construction (the original asphalt portions from Temescal Canyon to Ontario Avenue were dubbed I-15W on maps until 1974), but was never officially signed as such.<ref>{{cite web |url = http://www.interstate-guide.com/i-215_ca.html |archive-url = https://web.archive.org/web/20031011192726/http://www.interstate-guide.com/i-215_ca.html |url-status = dead |archive-date = October 11, 2003 |title = entry for Interstate 215 California |publisher = Interstate-guide.com |access-date = November 27, 2011 }}</ref> In Idaho, I-15 had a western branch near [[Pocatello, Idaho|Pocatello]] that connected I-15 and I-84 (then I-80N). This highway was designated I-15W. It is now the [[Interstate 86 (west)|western I-86]].<ref>{{cite web |url = http://www.interstate-guide.com/i-086_west.html |title = entry for I-86 Western |publisher = Interstate-guide.com |access-date = November 27, 2011 |archive-url = https://web.archive.org/web/20121019125648/http://www.interstate-guide.com/i-086_west.html |archive-date = October 19, 2012 |url-status = dead }}</ref>

===Growth along route===
Since the construction of I-15, California, Nevada, and Utah have consistently ranked in the fastest-growing areas of the United States. As a result, the route of I-15 has substantially increased in population and commuter traffic has increased the traffic burden on the freeway. Current population estimates are that more than 75&nbsp;percent of the population of Utah,<ref name=UTI>{{cite web |url = http://www.utah.com/visitor/state_facts/population.htm |title = Population-Visitor Center- Utah.com |access-date = January 2, 2008 |publisher = Utah Travel Industry |url-status = dead |archive-url = https://web.archive.org/web/20080117034523/http://www.utah.com/visitor/state_facts/population.htm |archive-date = January 17, 2008 |df = mdy-all }}</ref> 19&nbsp;percent of the population of California, and more than 70&nbsp;percent of the population of Nevada live in counties where I-15 is the primary [[Interstate Highway System|Interstate Highway]].

Similarly, in California, I-15 is seeing more commuter traffic due to the growth of the [[Mojave Desert]] communities of [[Hesperia, California|Hesperia]], [[Victorville, California|Victorville]], and [[Barstow, California|Barstow]]. In Utah, I-15 has been under near-constant construction in the [[Wasatch Front]], and future plans released by the [[UDOT|Utah Department of Transportation (UDOT)]] indicate that this will continue in the north ''and'' the far south of the state as well, due to the extremely rapid growth of [[Washington County, Utah|Washington County]] and surrounding areas. In like manner, [[Las Vegas]] in Nevada has seen growth along I-15, and in all of the states that it currently serves, it has recently been or is currently in the process of being widened.<ref name=udot>{{cite web |url = http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:69, |title = Utah Department of Transportation, Projects Under Construction |access-date = January 2, 2008 |publisher = Utah Department of Transportation |archive-date = May 21, 2012 |archive-url = https://web.archive.org/web/20120521232341/http://www.udot.utah.gov/main/f?p=100:pg:0:::1:T,V:69, |url-status = dead }}</ref><ref>{{cite web |url = http://www.nevadadot.com/Projects_and_Programs/Road_Projects/District_1_Construction_Report.aspx |title = District 1 Construction Report |access-date = January 2, 2008 |publisher = Nevada Department of Transportation |archive-url = https://web.archive.org/web/20110527065208/http://www.nevadadot.com/Projects_and_Programs/Road_Projects/District_1_Construction_Report.aspx |archive-date = May 27, 2011 |url-status = dead }}</ref><ref>{{cite web |url = http://www.dot.ca.gov/dist8/projects/15/I-15%20Brstw%20-STLN.revsd%206-2004%20copy.pdf |title = Interstate 15 Major Improvements |publisher = California Department of Transportation |url-status = dead |archive-url = https://web.archive.org/web/20070615184246/http://www.dot.ca.gov/dist8/projects/15/I-15%20Brstw%20-STLN.revsd%206-2004%20copy.pdf |archive-date = June 15, 2007 }}</ref> The portions in Arizona, Idaho and Montana have retained their rural, long-haul character. Although Arizona has also grown substantially since the construction of I-15, this [[highway]] serves only the [[Arizona Strip|isolated corner]] of northwestern Arizona.

Due to this rapid area growth, the I-15 corridor is the focus of several [[mass transit]] projects. The [[Las Vegas Monorail]], ''[[FrontRunner]]'' [[Commuter rail in North America|commuter rail]] system, and [[TRAX (light rail)|TRAX]] [[light rail]] in [[Salt Lake City]] are mass transit lines loosely parallel to I-15 that are now in operation.{{cn|date=June 2024}}

The Los Angeles–Las Vegas corridor has long been proposed as a high-speed [[Magnetic levitation train|maglev train]] route to relieve highway congestion. Proposals from as early as the 1970s were succeeded by the [[California–Nevada Interstate Maglev]] project, which was studied from 2004 to 2010 but never realized.<ref name="KTNV-Trains">{{cite news |last=Lupiani |first=Joyce |date=April 1, 2021 |title=History of train service between Las Vegas and California |url=https://www.ktnv.com/vegastrainhistory |publisher=[[KTNV-TV|KTNV]] |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053959/https://www.ktnv.com/vegastrainhistory |url-status=live }}</ref><ref>{{cite news |last=Velotta |first=Richard N. |date=March 3, 2024 |title=Before the LV-to LA rail project, maglev was planned |url=https://www.reviewjournal.com/business/business-columns/inside-gaming/before-the-lv-to-la-rail-project-maglev-was-planned-3010776/ |work=Las Vegas Review-Journal |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053943/https://www.reviewjournal.com/business/business-columns/inside-gaming/before-the-lv-to-la-rail-project-maglev-was-planned-3010776/ |url-status=live }}</ref> [[Amtrak]] ran a conventional passenger rail service between the two cities, named the ''[[Desert Wind]]'', from 1979 to 1997.<ref name="KTNV-Trains"/> The [[Brightline West]] line, a conventional [[high-speed rail]] service under a private operator, broke ground in 2024 and is scheduled to commence in 2028 with service between [[Rancho Cucamonga, California|Rancho Cucamonga]] and Las Vegas.<ref>{{cite news |last=Encinas |first=Amaris |date=April 23, 2024 |title=Brightline West broke ground, now the high-speed train is on the clock for 2028 Olympics |url=https://www.usatoday.com/story/travel/news/2024/04/23/brightline-west-train-route-map/73428402007/ |work=USA Today |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053958/https://www.usatoday.com/story/travel/news/2024/04/23/brightline-west-train-route-map/73428402007/ |url-status=live }}</ref> It will use the median of I-15 for most of its {{convert|218|mi|km|adj=mid}} route and reach speeds of up to {{convert|186|mph|kph}}.<ref>{{cite news |date=January 23, 2024 |title=Feds OK $2.5 billion more for high-speed rail from SoCal to Las Vegas; could open by 2028 |url=https://www.desertsun.com/story/news/nation/california/2024/01/23/high-speed-rail-from-las-vegas-to-southern-california-may-open-by-2028/72326897007/ |work=Desert Sun |accessdate=June 19, 2024 |archive-date=June 20, 2024 |archive-url=https://web.archive.org/web/20240620053943/https://www.desertsun.com/story/news/nation/california/2024/01/23/high-speed-rail-from-las-vegas-to-southern-california-may-open-by-2028/72326897007/ |url-status=live }}</ref>

== Future ==
The segment signed as SR&nbsp;15 from [[Interstate 5 in California|I-5]] to [[Interstate 8 in California|I-8]] in [[San Diego]] is planned to be redesignated as part of I-15 once this segment is completely converted to [[Interstate Highway standards|Interstate standards]], namely where the freeway's [[Interchange (road)|interchange]] with SR&nbsp;94 is concerned. The interchange currently has left-exits and blind merges, and is due to be updated with a widening of both SR&nbsp;15 and SR&nbsp;94. At that time, SR&nbsp;15 is planned be resigned as part of I-15. The remaining portion of SR&nbsp;15 conforms with Interstate standards.<ref name="cahighways.org">{{cite web|url=http://cahighways.org/009-016.html#015|title=Routes 9 through 16|last=Faigin|first=Daniel P.|work=California Highways|access-date=May 1, 2008|archive-date=July 9, 2016|archive-url=https://web.archive.org/web/20160709225634/http://www.cahighways.org/009-016.html#015|url-status=live}}{{self-published source|date=August 2014}}</ref>

==Junction list==
; California
: {{jct|country=USA|state=CA|I|8|SR|15|nolink2=yes}} in [[San Diego]]
: {{jct|country=USA|I|215|dab1=California}} in [[Murrieta, California|Murrieta]]
: {{jct|country=USA|I|10}} in [[Ontario, California|Ontario]]
: {{jct|country=USA|I|215|dab1=California}} in [[San Bernardino, California|San Bernardino]]
: {{jct|country=USA|US|395}} in [[Hesperia, California|Hesperia]]
: {{jct|country=USA|I|40}} in [[Barstow, California|Barstow]]
; Nevada
: {{jct|country=USA|I|215|dab1=Nevada}} in [[Enterprise, Nevada|Enterprise]]
: {{jct|country=USA|I|11|US|93|US|95}} in [[Las Vegas]]. I-15/US&nbsp;93 travels concurrently to northeast of [[North Las Vegas, Nevada|North Las Vegas]].
; Arizona
: No major junctions
; Utah
: {{jct|country=USA|I|70}} south-southwest of [[Cove Fort]]
: {{jct|country=USA|US|50}} north-northeast of [[Holden, Utah|Holden]]. The highways travel concurrently to [[Scipio, Utah|Scipio]].
: {{jct|country=USA|US|6}} in [[Santaquin, Utah|Santaquin]]. The highways travel concurrently to [[Spanish Fork, Utah|Spanish Fork]].
: {{jct|country=USA|US|189}} in [[Provo, Utah|Provo]]
: {{jct|country=USA|US|89}} in [[Lehi, Utah|Lehi]]. The highways travel concurrently to [[Draper, Utah|Draper]].
: {{jct|country=USA|I|215|dab1=Utah}} in [[Murray, Utah|Murray]]
: {{jct|country=USA|I|80}} in [[South Salt Lake, Utah|South Salt Lake]]. The highways travel concurrently to [[Salt Lake City]].
: {{jct|country=USA|US|89}} in Salt Lake City
: {{jct|country=USA|US|89}} in [[North Salt Lake, Utah|North Salt Lake]]
: {{jct|country=USA|I|215|dab1=Utah}} in North Salt Lake
: {{jct|country=USA|US|89}} on the [[West Bountiful, Utah|West Bountiful]]–[[Bountiful, Utah|Bountiful]] city line. The highways travel concurrently to [[Farmington, Utah|Farmington]].
: {{jct|country=USA|I|84|dab1=Oregon–Utah}} in [[Riverdale, Utah|Riverdale]]. The highways travel concurrently to [[Tremonton, Utah|Tremonton]].
: {{jct|country=USA|US|91}} on the [[Perry, Utah|Perry]]–[[Brigham City, Utah|Brigham City]] city line.
; Idaho
: {{jct|country=USA|US|91}} north-northwest of [[Virginia, Idaho|Virginia]]. The highways travel concurrently to [[Pocatello, Idaho|Pocatello]].
: {{jct|country=USA|US|30}} northwest of [[McCammon, Idaho|McCammon]]. The highways travel concurrently to Pocatello.
: {{jct|country=USA|I|86|dab1=Idaho}} in [[Chubbuck, Idaho|Chubbuck]]
: {{jct|country=USA|US|91}} southwest of [[Blackfoot, Idaho|Blackfoot]]
: {{jct|country=USA|US|26}} in Blackfoot. The highways travel concurrently to [[Idaho Falls, Idaho|Idaho Falls]].
: {{jct|country=USA|US|20}} in Idaho Falls. The highways travel concurrently through Idaho Falls.
; Montana
: {{jct|country=USA|I|90}} in [[Butte, Montana|Butte]]. The highways travel concurrently through Butte.
: {{jct|country=USA|I|115}} in Butte
: {{jct|country=USA|US|12|US|287}} in [[Helena, Montana|Helena]]. I-15/US&nbsp;287 travels concurrently to northeast of [[Wolf Creek, Montana|Wolf Creek]].
: {{jct|country=USA|I|315|US|89}} in [[Great Falls, Montana|Great Falls]]. I-15/US&nbsp;89 travels concurrently to northeast of [[Vaughn, Montana|Vaughn]].
: {{jct|country=USA|US|2}} in [[Shelby, Montana|Shelby]]
: {{jct|province=AB|Hwy|4}} at the [[Sweetgrass-Coutts Border Crossing]] in the [[Canada–United States border|Canadian border]] east-northeast of [[Sweet Grass, Montana|Sweet Grass]]

==Auxiliary routes==
*[[Inland Empire|Inland Empire, California]]&nbsp;– [[Interstate 215 (California)|I-215]]
*[[Las Vegas|Las Vegas, Nevada]]&nbsp;– [[Interstate 215 (Nevada)|I-215]], [[Interstate 515|I-515]] (former)
*[[Salt Lake City|Salt Lake City, Utah]]&nbsp;– [[Interstate 215 (Utah)|I-215]]
*[[Butte, Montana]]&nbsp;– [[Interstate 115|I-115]]
*[[Great Falls, Montana]]&nbsp;– [[Interstate 315|I-315]] (unsigned)

==See also==
{{Portal|U.S. Roads}}
* [[U.S. Route 66]]
* [[U.S. Route 91]]

==References==
{{Reflist}}

==External links==
{{Commons category|Interstate 15}}
{{Attached KML|display=title,inline}}
* {{osmrelation-inline}}
* https://web.archive.org/web/20030626140609/http://www.dot.ca.gov/dist11/facts/I-15managed.pdf
* 2005 Rand McNally ''The Road Atlas 2005''- newest feature- interstate mileage by state

; California
* [http://www.cahighways.org/009-016.html#015 California Highways: SR 15]
* [https://web.archive.org/web/20020417160041/http://www.dot.ca.gov/hq/traffops/signtech/calnexus/reports/fifteennorth.htm Cal-NExUS: Route 15 North]
* [https://web.archive.org/web/20020611090947/http://www.dot.ca.gov/hq/traffops/signtech/calnexus/reports/fifteensouth.htm Cal-NExUS: Route 15 South]

; Arizona
* [https://web.archive.org/web/20070111074759/http://www.interstate50th.org/history/2006-12-14.shtml I-15 Completed December 14, 1973]

{{I-15 aux}}
{{interstates}}
{{Authority control}}

{{DEFAULTSORT:I15}}
[[Category:Interstate 15| ]]
[[Category:Interstate Highway System|15]]
[[Category:U.S. Route 91]]