California State Route 58 is an east-west highway across the southern San Joaquin Valley, the Tehachapi Mountains, which borders the southern Sierra Nevada, and the Mojave Desert between its western terminus near Santa Margarita, California (junction U.S. Highway 101) and Barstow, California (junction Interstate 15). It has junctions with Interstate 5 near Buttonwillow, California State Route 99 in Bakersfield, California State Route 202 in Tehachapi, California State Route 14 near Mojave, and U.S. Highway 395 at Kramer Junction . Route 58 gives good access to Edwards Air Force Base.
Route 58 is entirely freeway between Bakersfield and several miles east of Mojave (a freeway bypass of Mojave was completed in 2004), except for two grade-level intersections two miles apart in the Caliente area. There is another grade level intersection east of Mojave and west of the main Edwards AFB north gate exit where California City Blvd. intersects it. Other freeway segments are bypasses of Boron and Barstow. Except for the Boron freeway bypass, CA 58 is a four lane expressway (two lanes per direction) just east of Mojave up to the Barstow bypass segment.
Route 58 takes the southernmost route through the Sierra Nevada and allows motorists to travel between the Central Valley and points to the east, such as Las Vegas, Nevada and Phoenix, Arizona without having to face the extreme traffic congestion of greater Los Angeles. California has long sought federal funds for an extension of Interstate 40 west of Barstow; any such extension would use the general path of Route 58, if not existing highway, as far west at least as Bakersfield, whose rapid growth has made it a significant generator of traffic in its own right. The desired highway is being built piecemeal as Caltrans has funds available.
Route 58 west of Buttonwillow is a winding mountain road through a thinly-populated area. Alternatives such as California State Route 46 to the north or California State Highway 166 (CA 166) to the south are recommended. However, this section of CA 58 does pass through the Carrizo Plain National Monument, which is known for its scenic beauty and geological features, including the San Andreas Fault.
Route 58 did not exist until 1964, when California decommissioned U.S. Highway 466, which was renamed CA 58 between Bakersfield and Barstow. West of Bakersfield, Route 58 incorporated the route of California State Highway 178 . Note that US 466 west of Bakersfield largely became CA 46.