Interstate 15 (I-15) is an Interstate Highway in the U.S. state of Nevada that begins in Primm, continues through Las Vegas and it crosses the border with Arizona in Mesquite. Within the state, the freeway runs entirely in Clark County. The highway was built along the corridor of the older U.S. Route 91 (US 91) and Arrowhead Trail, eventually replacing both of these roads.

The entire route of I-15 is designated the Las Vegas Freeway.

Motorists in California begin a long descent through Ivanpah Valley and Ivanpah Dry Lake. I-15 crosses the Nevada state line at the first exit, Primm. Once I-15 leaves Primm, the route travels north through the desert with few services. The highway then enters the Las Vegas urban area upon passing the State Route 146 (SR 146, Saint Rose Parkway) interchange.

From Silverado Ranch Boulevard to US 95, the freeway has HOV lanes that are currently enforced by both Metro and NHP, 24 hours a day and 7 days a week and is the only state within the nation to do so.

The Interstate meets I-215 at the Southern Beltway Interchange, which provides access to Henderson and Harry Reid International Airport. Originally, this interchange was termed Son of Spaghetti Bowl by the Las Vegas Review-Journal when it was built.

I-15 travels along the west side of the Las Vegas Strip corridor and just west of downtown Las Vegas just before its junction with I-11 and US 95 (the "Spaghetti Bowl" interchange). Then, the Interstate enters North Las Vegas and continues to run roughly parallel to Las Vegas Boulevard (old US 91) as it leaves the Las Vegas urban limits near the northern junction with the Clark County 215 beltway.

Once I-15 leaves North Las Vegas, the freeway travels northeast and crosses the Muddy River at Glendale and then climbs up onto the Mormon Mesa. At Mesquite, the freeway then crosses the Arizona state line and cuts through the extreme northwestern corner of Arizona through the Virgin River Gorge before entering Utah.

The general location of the I-15 corridor through Nevada can be traced as far back as the early 1900s. Regular automobile travel through southern Nevada was established by 1914 along the Arrowhead Trail, a road connecting Los Angeles and Salt Lake City. In 1919, the Nevada Legislature amended its newly adopted highway law to add SR 6, which was described as "Commencing at the Arizona line near Mesquite and running southwesterly over what is now known as the Arrow Head [sic] trail through Las Vegas to Jean, Nevada." Two years later, the route was revised to pass through Las Vegas and head "via Jean or Goodsprings to a junction with the California state highway system."

US 91 was later proposed as part of the original 1925 U.S. Highway System plan. As originally proposed, US 91 would have followed SR 6 southwest from Mesquite to downtown Las Vegas, where it would then turn southeast along SR 5 to California via Searchlight. The revised 1926 plan had proposed US 91 follow SR 6 through Las Vegas and Jean to the California state line. Nevada's 1927 official highway map reflects the routing of the final 1926 plan; however, a few maps from the era indicate the original proposal.

US 91 / SR 6 began at Primm and followed the Los Angeles Highway toward Las Vegas. Within the city limits, it ran along Fifth Street (now Las Vegas Boulevard) through downtown and into North Las Vegas, where it departed from 5th at Main Street. Exiting the Las Vegas area to the northeast, US 91 became the Salt Lake Highway and then headed toward Apex and Glendale. The highway then curved east-northeast before following present-day SR 170 through Riverside and Bunkerville into Mesquite. US 91 was routed through that city on Mesquite Boulevard, Sandhill Boulevard and Fairview Avenue before crossing the Arizona state line. By 1929, the alignment of US 91 / SR 6 was graded throughout much of the state, a distance of 129.5 miles (208.4 km).

The route eventually gained two other highway overlaps. US 466 was christened in 1934, and was routed concurrently along US 91 from California to downtown Las Vegas before heading southeast to Hoover Dam (the route was deleted in 1971). Also, in 1936, US 93 was extended from its 1932 southern terminus at Glendale, over US 91 to downtown Las Vegas on its way to Hoover Dam.

A new alignment of US 91 was completed in 1955. This bypassed both Bunkerville and Mesquite to the northwest, along what would become the future path of I-15. The original alignment through Bunkerville is now SR 170.

The passage of the Federal Aid Highway Act of 1956 quickly brought upgrades to the US 91 corridor. The first section of the newly designated I-15 opened by 1960. This stretch extended from the California state line to just north of Sloan. In 1963, the new freeway reached the south end of the Las Vegas Valley at Blue Diamond Road, and more than 20 miles (32 km) south of Glendale was also finished. By 1967, I-15 had been constructed along the entire length of US 91 except through parts of Las Vegas and near Mesquite.

The final sections of I-15 to be completed were in North Las Vegas and near the Arizona state line. Both of these sections were completed in 1974. The US 91 designation, which had remained on its original alignment during the construction of the Interstate, was made redundant by the new freeway and was removed in 1974.

Between Las Vegas and the California state line, the Nevada Department of Transportation (NDOT) added call boxes at one-mile (1.6 km) intervals in the mid-2000s, for motorists with vehicle problems and without cell phone service. This was done as part of a larger project that expanded this portion of the freeway to three travel lanes in each direction to coordinate with a similar effort in California.

In August 2011, I-15 in southern Las Vegas was substantially expanded. This involved adding between 30 and 85% more capacity and involved the use of the Big Stan drill rig.

Due to heavy traffic, there are plans by the California Department of Transportation (Caltrans) and NDOT to widen I-15 in both directions from both US 395 in Hesperia and I-40 in Barstow to I-215 in Enterprise.

In 2020, Brightline signed a 50-year lease for use of the I-15 right-of-way between Victor Valley and the Las Vegas Valley for use in their Brightline West high-speed rail service.

The entire route is in Clark County.

Location	mi	km	Exit	Destinations	Notes
Primm	0.00	0.00	—	I-15 south – San Bernardino, Los Angeles	Continuation into California; former US 91 south/US 466 west
	0.39	0.63	1	Primm (Primm Boulevard)
Jean	12.63	20.33	12	SR 161 west (Goodsprings Road) – Jean, Goodsprings
Enterprise	25.52	41.07	25	Sloan (Via Inspirada)	Proposed interchange upgrade; former SR 739 east; Via Inspirada was formerly Sloan Road
	27.84	44.80	27	SR 146 east (Saint Rose Parkway) / Southern Highlands Parkway – Henderson, Lake Mead
	29.37	47.27	29	Starr Avenue
	30.39	48.91	30	Cactus Avenue
	31.36	50.47	31	Silverado Ranch Boulevard	Southern end of I-15 HOV lanes
	33.55	53.99	33	SR 160 (Blue Diamond Road) – Pahrump
	34.85	56.09	34	I-215 east / CC 215 west / Las Vegas Boulevard – McCarran Airport, Henderson	Northbound exit is part of exit 33; southbound exit to CC 215 west is part of exit 36; future I-215 west; I-215 exit 12
Paradise	36.39	58.56	36	Russell Road	Signed as exit 35 northbound; northbound also includes exit to Frank Sinatra Drive; former SR 594
	37.40	60.19	37	Tropicana Avenue (SR 593)	Signed as exit 36 northbound; northbound also includes exit to Frank Sinatra Drive
	37.90	60.99	♦	Harmon Avenue	The Harmon Half Interchange, a northbound-only left HOV exit created by the Tropicana Avenue road project in 2024.
	38.35	61.72	38	Flamingo Road (SR 592 west)	Signed as exits 38A (west) and 38B (east) southbound
	39.16	63.02	39	Spring Mountain Road	Former SR 591
Las Vegas	40.55	65.26	40	Sahara Avenue	Former SR 589
	41.47	66.74	♦	Neon Gateway (Western Avenue)	HOV interchange
	41.75	67.19	41	SR 159 (Charleston Boulevard)	Northbound ramps also include access to Alta Drive, Bonneville Avenue and Grand Central Parkway; serves University Medical Center of Southern Nevada and Valley Hospital Medical Center
	42.89	69.02	42	I-11 / US 93 south / US 95 / Martin L. King Boulevard – Downtown Las Vegas, Phoenix, Reno	Spaghetti Bowl Interchange; Northern end of I-15 HOV lanes; southern end of US 93 concurrency; HOV access to US 95 north; signed as exits 42A (north) and 42B (south) northbound; I-11/US 95 exit 76 future exit 37; former I-515 south
	43.47– 43.60	69.96– 70.17	43	D Street, City Parkway, Washington Avenue (SR 578 east)	Signed as exit 44 southbound
North Las Vegas	44.72	71.97	45	Lake Mead Boulevard (SR 147 east)	Serves North Vista Hospital
	46.43	74.72	46	Cheyenne Avenue (SR 574)
	48.41	77.91	48	Craig Road (SR 573)
	50.13	80.68	50	Lamb Boulevard (SR 610 south)
	52.00	83.69	52	CC 215 west / Tropical Parkway	Signed as exits 52A (CC-215 west) and 52B (Tropical Parkway) northbound future I-215 west
	53.62	86.29	54	Speedway Boulevard, Hollywood Boulevard
	58.14	93.57	58	SR 604 south (Las Vegas Boulevard) – Apex, Nellis AFB	Former US 91/US 93
Garnet	64.29	103.46	64	US 93 north (Great Basin Highway) – Ely	Northern end of US 93 concurrency; Diverging diamond interchange
Crystal–Moapa River Indian Reservation line	75.67	121.78	75	Valley of Fire, Lake Mead (Valley of Fire Highway)
Moapa River Indian Reservation	80.76	129.97	80	Ute
​	84.54	136.05	84	Byron
​	88.68	142.72	88	Hidden Valley (Hidden Valley Road)
Glendale–Moapa line	90.84	146.19	90	SR 168 west (Glendale–Moapa Road) – Glendale, Moapa	Northbound exit and southbound entrance; SR 168 west was former US 93 north
	91.61	147.43	91	Glendale, Moapa (Glendale Boulevard, Lewis Ranch Road)	No southbound entrance
Moapa Valley	93.89	151.10	93	SR 169 south (Moapa Valley Boulevard) – Logandale, Overton
​	100.43	161.63	100	Carp, Elgin (Carp–Elgin Road)
Mesquite	112.01	180.26	112	SR 170 east (Riverside Road) – Riverside, Bunkerville	SR 170 east was former US 91 north
	118.14	190.13	118	Lower Flat Top Drive
	120.34	193.67	120	Falcon Ridge Parkway, Mesquite Boulevard	Dumbbell interchange; Mesquite Boulevard was former I-15 Bus. north/SR 144 north
	122.90	197.79	122	Pioneer Boulevard, Sandhill Boulevard	Sandhill Boulevard was former I-15 Bus. south/SR 144 south
	123.76	199.17	—	I-15 north (Veterans Memorial Highway) – Salt Lake City	Continuation into Arizona
1.000 mi = 1.609 km; 1.000 km = 0.621 mi       Concurrency terminus       HOV only       Incomplete access

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