State Route 58 (SR 58) is an east-west highway across the California Coast Ranges, the southern San Joaquin Valley, the Tehachapi Mountains, which border the southern Sierra Nevada, and the Mojave Desert. It runs between its western terminus near Santa Margarita (junction U.S. Route 101) and its eastern terminus at Barstow (junction Interstate 15). It has junctions with Interstate 5 near Buttonwillow, State Route 99 in Bakersfield, State Route 202 in Tehachapi, State Route 14 in Mojave, and U.S. Route 395 at Kramer Junction. Route 58 gives good access to Edwards Air Force Base.

This route is part of the California Freeway and Expressway System and is eligible for the State Scenic Highway System. However, it is not a scenic highway as designated by Caltrans.

Route 58 has several names throughout its length, including the Blue Star Memorial Highway (for its entire length); the Kern County Korean War Veterans Memorial Highway, for the section from Route 184 to the Kern County/San Bernardino County Line; and the Rosa Parks Highway, for the section between Route 99 and Route 184. The Korean War Veterans name honors the approximately 8,120 veterans from Kern County, while the section named for Rosa Parks honors the civil rights activist. The portion of the 58 from Barstow to Bakersfield is sometimes referred to as the Barstow–Bakersfield Highway.

Route 58 is a freeway from its south junction with Route 99 in Bakersfield (West Bakersfield Interchange) to several miles east of Mojave (a freeway bypass of Mojave was completed in 2004), except for two grade-level intersections two miles (3.2 km) 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, SR 58 is primarily a four lane expressway (two lanes per direction) just east of Boron up to the Barstow bypass segment with the exception of the portion of Route 58 between Boron and approximately 5 miles (8.0 km) east of Kramer Junction, which is currently two-lane highway and is not yet expressway.

Route 58 takes the southernmost route through the Sierra Nevada and allows motorists to travel between Northern California and points to the east, such as Las Vegas and Interstate 40 without having to face the extreme traffic congestion of greater Los Angeles. Route 58 and Interstate 80 are the only freeways to cross the Sierra Nevada. The route also offers an alternative to the often treacherous Donner Pass to truckers traveling from the San Francisco Bay Area to points eastward; prior to the construction of Interstate 80, the road (as U.S. Route 466) was heavily used for this purpose.

Route 58 west of Buttonwillow is a winding mountain road through a thinly-populated area. Alternatives such as State Route 46 to the north or State Route 166 to the south are recommended, such as on signage approaching the western terminus of Route 58 from US 101, for those not wishing to traverse so mountainous a route; much of this section of Route 58 is prohibited to truck traffic. However, this section of SR 58 does pass through the Carrizo Plain, which is known for its scenic beauty and geological features, including the San Andreas Fault.

Route 58 did not exist as a California sign route until 1964 although previous to 1964 it was part of California legislative route 58. The other part of legislative route 58 is California's segment of Interstate 40; previous to 1964 it was a segment of US 66.

Prior to 1964 the segment of SR 58 between Bakersfield and Barstow was signed U.S. Route 466. Also at that time, the segment of Route 58 between State Route 33 at McKittrick and Route 99 in Bakersfield was signed as State Route 178. Although it was proposed for signing as Route 178 in 1934, the segment of legislative route 58 between US 101 near Santa Margarita and State Route 33 at Mc Kittrick was not signed prior to 1964.

Note that US 466 was co-signed with US 99, now State Route 99, between Bakersfield and Famoso Junction. Between Famoso and US 101 at Paso Robles, US 466 largely became SR 46.

The eastern terminus was originally at I-15 north of Barstow. Route 58 was rerouted to I-15 in Barstow south of the I-40 interchange. The former eastern terminus is now known as "Old Highway 58."

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, at least between Mojave and Barstow. A Bakersfield Beltway is also proposed. Two at-grade intersections within 1 + 1⁄2 miles (2.4 km) of each other around mile 76, roughly halfway between Bakersfield and Mojave, would have to be either closed or upgraded to interchanges for the whole of Route 58 to be up to Interstate standards, and the at-grade junction of Route 58 and US 395 in Kramer Junction is further complicated by the nearby Union Pacific Railroad Tehachapi line (a busy single track over which BNSF also operates) which Route 58 also crosses at grade 2 + 1⁄2 miles (4.0 km) to the west.

The San Luis Obispo Planning Commission is considering a permit application for the California Valley Solar Ranch and has released a Draft Environmental Impact Report with a public comment period closure date November 1, 2010. Among the points raised in the DEIR is the aesthetic impact on the viewshed which would be particularly troublesome if large industrial scale arrays of solar panels are placed north of Route 58 in the section of road just east of Soda Lake Road.

State Route 58 Business is a business route of California State Route 58 in Mojave. It provides access to downtown Mojave as Mojave-Barstow Highway. It also follows the former routing of U.S. Route 6 and U.S. Route 466.

State Route 58 Business is a business route of California State Route 58 in Tehachapi. It provides access to downtown Tehachapi as Tehachapi Boulevard. It also follows the former routing of U.S. Route 466 and is overlapped with State Route 202.

State Route 58 Business is a business route of California State Route 58 in Boron. It provides access to downtown Boron as Twenty Mule Team Road. It also follows the former routing of U.S. Route 466. It is signed from westbound Route 58 approaching the San Bernardino–Kern county line and the beginning of the Boron bypass.

Except where prefixed with a letter, postmiles were measured on the road as it was in 1964, and do not necessarily reflect current mileage. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.