For the historic Highway 40 in Northern California, see U.S. Route 40 in California.
Interstate 40 in California
I
StateCA
Route40
Alternate nameNeedles Freeway
MaintCaltrans
Length154.64 mi
Length round3
Established1964
Direction aWest
Terminus ain Barstow
Junctionin Needles
Direction bEast
Terminus bat the Arizona state line near Topock, AZ
CountiesSan Bernardino
Previous route39
Next route41

Interstate 40 (I-40) is a major east–west Interstate Highway in the United States, stretching from Barstow, California, to Wilmington, North Carolina. The segment of I-40 in California is sometimes called the Needles Freeway. It passes through the eastern fringe of the Inland Empire metropolitan area, going east from its western terminus at I-15 in Barstow across the Mojave Desert in San Bernardino County past the Clipper Mountains to Needles, before it crosses over the Colorado River into Arizona east of Needles. All 155 miles (249 km) of I-40 in California are in San Bernardino County.

Route description

The entirety of Interstate 40 in California is defined in section 340 of the California Streets and Highways Code as Route 40, and that the highway is from "Route 15 at Barstow to the Arizona state line near Topock, Arizona via Needles."[1] This corresponds with the Federal Highway Administration (FHWA)'s route logs of I-40.[2]

I-40 goes through the Mojave Desert on the entirety of its run through California. The highway starts its eastward journey at a junction with I-15 in Barstow. The freeway passes through Marine Corps Logistics Base Barstow before leaving the city limits. I-40 provides access to the town of Daggett but passes south of the town. After passing south of the Barstow-Daggett Airport, I-40 goes through Newberry Springs and Ludlow before traveling along the south end of Mojave National Preserve. Several miles east of the preserve, I-40 intersects U.S. Route 95 (US 95), and the two highways run concurrently into the city of Needles. In Needles, US 95 continues south while I-40 continues east through Mojave National Preserve and across the Colorado River into Arizona.[3] The maximum speed limit for the entire California segment of I-40 is 70 mph (110 km/h).

I-40 is part of the California Freeway and Expressway System and is part of the National Highway System,[4][5] a network of highways that are considered essential to the country's economy, defense, and mobility by the Federal Highway Administration.[6] I-40 is eligible for the State Scenic Highway System,[7] but it is not officially designated as a scenic highway by the California Department of Transportation.[8] I-40 from I-15 to the Arizona state line is known as the Needles Freeway, as named by Senate Concurrent Resolution 1 in 1968.[9]

History

In 1957, the California Department of Highways proposed that the route be numbered as I-30 because of the already existing US 40 in the state. However, this was rejected, and, eventually, US 40 was decommissioned in favor of I-80.

Today, the Needles Freeway replaced the former US 66 across the Mojave Desert. As a result, a number of communities along the former route, like Amboy, have become ghost-towns.[10]

In the early 1960s, Project Carryall, a component of Project Plowshare, would have detonated 22 nuclear explosions to excavate a massive roadcut through the Bristol Mountains to accommodate a better alignment of I-40 and a new rail line. This proposal was abandoned by the California State Department of Highways in 1968.[11][12] The section between Ludlow and Needles was constructed using conventional explosives and excavation and designed with culverts for migrating Bighorn sheep and water tanks. It opened to traffic on April 13, 1973.[13]

A sign at that start of I-40 in Barstow showing the distance to Wilmington, North Carolina, had been stolen multiple times.[14]

California does not have any auxiliary Interstate Highways associated with I-40.

One business loop of I-40 exists in the state, running through Needles. It is also designated as Historic Route 66 since it follows the former routing of US 66.

References

  1. ^ "Section 340". California Streets and Highways Code. Sacramento: California Office of Legislative Counsel. Retrieved August 17, 2025.
  2. ^ "Table 1: Main Routes of the Dwight D. Eisenhower National System Of Interstate and Defense Highways". FHWA Route Log and Finder List. Federal Highway Administration. Retrieved August 17, 2025.
  3. ^ San Bernardino County Street Atlas. Thomas Brothers. 2008.
  4. ^
  5. ^
  6. ^
  7. ^
  8. ^
  9. ^
  10. ^ Anton, Mike (January 17, 2007). "Destiny in the desert". Los Angeles Times. Retrieved November 29, 2011.
  11. ^ "Project Carryall Marker". Hmdb.org. January 9, 2012. Retrieved January 25, 2013.
  12. ^ Fry, J. G.; Stane, R. A.; Crutchfield Jr, W. H. (July 26, 1994). "Preliminary Design Studies In A Nuclear Excavation: Project Carryall". TRB Publications Index. ' (50). Retrieved January 25, 2013.
  13. ^ "Barstow-Needles highway realigned for 67 miles". Redlands Daily Facts. April 14, 1973. p. 9. Retrieved August 30, 2023. – via Newspapers.com
  14. ^ "I-40 Barstow, Calif., sign gone for good". Star-News. November 13, 2009. Archived from the original on March 7, 2012. Retrieved November 13, 2009.