Exit 175, Outlet Center Drive, Interstate 15 Northbound, 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 Route 15 is 293.64 miles (472.57 km).