Interstate 15 in California

Interstate 15 and State Route 15
Route information
Defined by
Maintained by Caltrans
Length:	293.64 mi (472.57 km)
Existed:	1957 – present
Component highways:	SR 15 from 32nd Street in San Diego to I-8 I-15 from I-8 to Nevada state line
Major junctions
South end:	I-5 / 32nd Street / Norman Scott Road in San Diego
	I-805 in San Diego I-8 in San Diego I-215 in Murrieta I-10 in Ontario SR 210 in Rancho Cucamonga I-215 in San Bernardino US 395 in Hesperia SR 58 in Barstow I-40 in Barstow
North end:	I‑15 at Nevada state line
Highway system
Interstate Highway System Main Auxiliary Suffixed Business Future State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic ← SR 14 SR 16 →

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, a short section of Arizona, Utah, Idaho, and Montana to the Canada–US 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.

...
Wikipedia