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 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.