Interstate 15 in California

Route 15, consisting of the contiguous segments of State Route 15 (SR 15) joined by Interstate 15 (I-15), is a major north–south state highway in the U.S. state of California, connecting San Bernardino, Riverside, and San Diego Counties. The route consists of the southernmost 287.26 miles (462.30 km) of I-15, a major Interstate Highway that extends north through Nevada, Arizona, Utah, Idaho, and Montana to the Canadian border. It is a major thoroughfare for traffic between San Diego and the Inland Empire, as well as between Southern California, Las Vegas, Nevada, and points beyond.

South of its junction at Interstate 8 in San Diego, the highway becomes SR 15, extending 5.59 miles (9.00 km) to Interstate 5, about 12 miles (19 km) from the Mexican border. This segment was initially signed as a state route instead of an Interstate, but it is being upgraded to Interstate standards so it would become part of I-15 in the future. Including this segment, the entire length of Route 15 is 293.64 miles (472.57 km).

I15

I15 may refer to:

Interstate 15 in Nevada

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. The freeway runs entirely in Clark County. Many motorists use I-15 to visit Las Vegas, as it is the only primary Interstate Highway in the city. The highway was built along the corridor of the older U.S. Route 91 (US 91) and Arrowhead Trail, eventually replacing both of these designations.

Route description

Motorists in California leave the mountainous Mojave Desert and 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. Quickly thereafter, the Interstate meets I-215 at the Southern Beltway Interchange, which provides access to Henderson and McCarran International Airport. Originally, this interchange was termed Son of Spaghetti Bowl by the Las Vegas Review-Journal when the interchange was built.

Interstate 15 in Montana

In the U.S. state of Montana, Interstate 15 continues onward from Idaho for nearly 400 miles (640 km) through the cities of Butte, Helena and Great Falls, intersecting with Interstate 90, Interstate 115 and Interstate 315. Interstate 15 reaches its northern terminus at the international border with Alberta, Canada.

Interstate 15 joins with I-90 and makes a junction with a short, one-mile (1.6 km) spur route Interstate 115 in Butte.

Route description

I-15 crosses into Montana from Idaho just south of Lima Reservoir, before the route continues northwest through farmland and desert. The freeway turns north at Clark Canyon Reservoir, before turning northeast. In the town of Dillon, I-15 passes near Clark's Lookout State Park before beginning to parallel the Big Hole River. The freeway then turns away from the river, continuing northeast along Divide Creek through the desert, before splitting away from the creek and heading north. I-15 eventually merges into I-90 at a trumpet interchange.