Interstate 15 in California - Route Description

Route Description

Interstate 15 is part of the California Freeway and Expressway System, and it is eligible for designation as a state highway within the State Scenic Highway System; however the state transportation authority, Caltrans, has not done so. There are various local names for the highway, such as the Escondido Freeway between San Diego and Escondido. I-15 between SR 163 and Pomerado Road/Miramar Road is known as the Semper Fi Highway in recognition of the nearby Marine Corps Air Station Miramar. North of the Escondido city limits it is known as the Avocado Highway, whose designation ends upon entering Temecula. There are other local names as noted below.

Heading northward, I-15 currently begins at Interstate 8, at the same place that its continuation, State Route 15, begins its southward journey. I-15 goes through Mission Valley and intersects with State Route 52, before merging with State Route 163. After traversing the Marine Corps Air Station Miramar, I-15 comes into Rancho Peñasquitos, where it intersects with the end of State Route 56. Northward, the route crosses Lake Hodges inside the upper San Diego city limits. I-15 continues north into Escondido, where it interchanges with State Route 78. There are high-occupancy toll lanes in the center of I-15 from State Route 163 to State Route 78.

North of Escondido, I-15 goes through hilly terrain and farmland, descending to the town of Fallbrook and intersecting State Route 76 (SR 76), before it crosses the county line into Riverside County and descends to the Inland Empire. In Riverside County, SR 79 runs concurrently with I-15 for a four-mile (6 km) portion in Temecula, before it splits away running north to Hemet. Then, I-15 intersects with the southern end of Interstate 215, which continues the designation of the Escondido Freeway. Interstate 15 continues north as the Temecula Valley Freeway.

In Murrieta, I-15 splits from its first and only spur route in California, Interstate 215, which runs through the two largest cities in the Inland Empire, San Bernardino and Riverside. I-15 runs along the eastern edge of the Santa Ana Mountains, passing the town of Lake Elsinore. It continues through the suburban areas in the western Inland Empire, passing Corona and Ontario, California. The highway is then rejoined by I-215, before heading northwards and upward through the Cajon Pass, an important mountain pass that is the primary route between Southern California and points eastwards and northeastwards.

The portion of I-15 that is located between its northern and southern junctions with I-215 is also used by many local residents as the major north–south route for the western portions of the San Bernardino-Riverside-Ontario metropolitan area. (I-215 serves a similar function in the eastern portion of the metropolitan area. These two highways are the only continuous north–south freeways in the area.)

North of Limonite Avenue (south of SR 60), I-15 is known as the Ontario Freeway. I-15 intersects State Route 60, Interstate 10, and State Route 210 in rapid succession as it goes through Mira Loma, Ontario, and Rancho Cucamonga. As it nears Devore, I-15 merges with Interstate 215, where it is called the Barstow Freeway or the Mojave Freeway.

North of the Cajon Pass, I-15 traverses the Mojave Desert towns of Hesperia and Victorville. I-15 passes through desert for 30 miles (48 km) before reaching Barstow, then continues past Zzyzx Road, before reaching the town of Baker. The sign for Zzyzx Road — alphabetically the last place name in the world — is a landmark of sorts on the drive between Los Angeles and Las Vegas. I-15 enters Nevada near the casino town of Primm, formerly known as Stateline, Nevada.

I-15 continues thereafter to Las Vegas, Salt Lake City, and on into Idaho and Montana, before ending at the Canadian border, where Alberta Highway 4 continues the ribbon of asphalt into Canada. Because it joins with the western end of I-70 in Southwestern Utah, I-15 also forms part of a major east–west corridor connecting Southern California with Denver, St. Louis, and points east.

The Mojave Freeway is fairly busy on weekdays, since it connects the rapidly growing exurbs of the Victor Valley with the Los Angeles area. On weekends and holidays, however, it can sometimes be jammed with Californians driving to Las Vegas for short vacations.

Construction is currently underway to rehabilitate the pavement on I-15 and to add truck lanes to separate autos from truck traffic.