The highway then enters the Las Vegas urban area upon passing the State Route 146 (SR 146, Saint Rose Parkway) interchange.

[2][3] The Interstate meets I-215 at the Southern Beltway Interchange, which provides access to Henderson and Harry Reid International Airport.

[4] 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.

Regular automobile travel through southern Nevada was established by 1914 along the Arrowhead Trail, a road connecting Los Angeles and Salt Lake City.

"[6] 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.

[citation needed] The revised 1926 plan had proposed US 91 follow SR 6 through Las Vegas and Jean to the California state line.

Exiting the Las Vegas area to the northeast, US 91 became the Salt Lake Highway and then headed toward Apex and Glendale.

[18] 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.

[19] 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.