Interstate 10 in California

Interstate 10, often called I-10, is a major highway that stretches all the way from Santa Monica, California to Jacksonville, Florida. In California, this part of the highway is known as the Pearl Harbor Memorial Highway. It begins in Santa Monica and moves eastward through big cities like Los Angeles and San Bernardino, passing by beautiful places such as Palm Springs before entering Arizona.

In the busy area around Los Angeles, people call I-10 the Santa Monica and San Bernardino freeways. These two parts connect for a short distance on another highway, I-5, which is known as the Golden State Freeway. Special parts of I-10 are also named the Rosa Parks and Sonny Bono Memorial freeways.

For a long time, some parts of I-10 were called the Christopher Columbus Transcontinental Highway, but in 2022, the California State Legislature decided to remove that name. Many people in Southern California simply refer to the highway as "the 10".

Route description

Time-lapse video of a trip on I-10 from Baldwin Park to its western terminus in Santa Monica

I-10 is signed as if it begins at the McClure Tunnel in Santa Monica, although it legally begins farther east at the SR 1 interchange at Lincoln Boulevard.

A typical traffic jam on the Santa Monica Freeway, at 2:30 pm on a Wednesday afternoon near Robertson Boulevard

Downtown Los Angeles skyline as seen from the freeway. A slight (smaller than usual rush hour) traffic jam is ahead.

The Dosan Ahn Chang Ho Memorial Interchange (I-110), as seen by traffic going westbound on the Santa Monica

Heavily defaced button copy sign marking an entrance to the Santa Monica Freeway in Downtown Los Angeles, 2005

Interchange with the Ontario Freeway (I-15) as seen by westbound traffic on the San Bernardino Freeway

Heavy traffic from Downtown San Bernardino along the San Bernardino Freeway near the interchange with I-215

Cabazon Dinosaurs is a roadside attraction at the Main Street exit in Cabazon

I-10 eastbound in Whitewater at the exit for SR 111, looking east with the San Gorgonio Pass wind farm in the background. Note the overhead sign which gives "Indio [¶] Other Desert Cities" as the control cities.

I-10 eastbound near Indio

The entirety of Interstate 10 in California is defined in section 310 of the California Streets and Highways Code as Route 10, and that the highway is from:

(a) Route 1 [State Route 1 (SR 1)] in Santa Monica to Route 5 [I-5] near Seventh Street in Los Angeles.
(b) Route 101 [US Route 101 (US 101)] near Mission Road in Los Angeles to the Arizona state line at the Colorado River via the vicinity of Monterey Park, Pomona, Colton, Indio, and Chiriaco Summit and via Blythe.

Because I-10 west of I-5 cannot access US 101, and I-10 east of I-5 cannot access US 101 southbound, signage instead directs motorists to the continuation of I-10 via I-5 between the East Los Angeles Interchange and the Santa Monica Freeway. The Federal Highway Administration (FHWA)'s Interstate Highway route logs, along with most maps, also indicate that I-10 is cosigned along this segment, despite the legal definition. The short unsigned section of Route 10 between Route 5 and Route 101, which was formerly defined as Route 110 (signed as I-110) until 1968, carries overhead signage for I-10 eastbound and for US 101 westbound.

I-10 is part of the California Freeway and Expressway System and is part of the National Highway System, a network of highways that are considered essential to the country's economy, defense, and mobility by the FHWA. I-10 is eligible to be included in the State Scenic Highway System, but it is not officially designated as a scenic highway by Caltrans. The Santa Monica Freeway is I-10 from SR 1 to I-5, as named by the State Highway Commission on April 25, 1957. The section between the Harbor (I-110) and San Diego (I-405) freeways is also signed as the Rosa Parks Freeway, after the African-American civil rights activist. The I-10 freeway is signed as the Christopher Columbus Transcontinental Highway in Santa Monica. The removal of this designation, however, may result in the eventual removal of this signage.

Santa Monica Freeway

Not to be confused with Santa Monica Boulevard.

The Santa Monica Freeway is the westernmost segment of I-10, beginning at the east end of the McClure Tunnel in Santa Monica and ending southeast of Downtown Los Angeles at the East Los Angeles Interchange.

I-10 begins its eastward journey in the city of Santa Monica after SR 1 turns east through the McClure Tunnel. Note that the McClure Tunnel is part of SR 1 in its entirety, and the western terminus of I-10 is to the east of the tunnel at 4th Street. SR 1 then exits onto Lincoln Boulevard and heads south while I-10 continues east. Soon after it enters the city of Los Angeles, I-10 has a four-level interchange with I-405. I-10 then continues through Sawtelle, Rancho Park, Cheviot Hills, Beverlywood, and Crestview in West Los Angeles; Lafayette Square and Wellington Square in Mid City; and Arlington Heights, West Adams, and Jefferson Park into Downtown Los Angeles. On the western edge of downtown at the Dosan Ahn Chang Ho Memorial Interchange, I-10 has an interchange with I-110 to the south and SR 110 to the north. I-10 then travels along the southern edge of downtown to the East Los Angeles Interchange.

At the East Los Angeles Interchange, SR 60 diverges east toward Riverside and Pomona. I-10 then turns north, running concurrently with I-5 for approximately 1.5 miles (2.4 km). Then, I-10 heads east and merges with the traffic from the spur to US 101 onto the San Bernardino Freeway.

The freeway is 14 lanes wide (two local and five express lanes in each direction) from the Harbor Freeway (I-110) interchange to the Arlington Avenue offramp. Most of these lanes are full at peak travel times (even on Saturdays). The remainder of the freeway varies between eight and 10 lanes in width. The whole freeway opened in 1965 with four to six lanes, with a formal dedication held in 1966.

While the construction of the Century Freeway several miles to the south reduced traffic congestion to a considerable amount by creating an alternate route from downtown to Los Angeles International Airport, the Santa Monica Freeway is still one of the busiest freeways in the world. All three freeway-to-freeway interchanges along its length are notorious for their congestion and are routinely ranked among the top 10 most congested spots in the US.^{[citation needed]}

Due to the high traffic volume, car accidents are so common that Caltrans has constructed special accident investigation sites separated from the freeway by fences. These enable the California Highway Patrol to quickly clear accidents from the through traffic lanes, and the fences reduce congestion by preventing rubbernecking (in which vehicles slow down so their occupants can watch the accident investigation).

The Santa Monica Freeway is considered the border between Downtown and South Los Angeles. Part of the freeway also skims the Byzantine-Latino Quarter.

San Bernardino Freeway

I-10 heads east from the East Los Angeles Interchange to I-710 in Monterey Park. It then continues through the San Gabriel Valley suburbs of Alhambra, Rosemead, San Gabriel, El Monte, and Baldwin Park before intersecting with I-605. It then travels through West Covina, briefly enters Covina, and then travels up the Kellogg Hill into San Dimas, where I-10 intersects with SR 57 (formerly part of I-210) and SR 71 at the Kellogg Interchange. I-10 then heads east through Pomona and Claremont, leaving Los Angeles County to enter San Bernardino County.

In San Bernardino County, I-10 travels through Montclair, Upland, and Ontario, providing access to Ontario International Airport. I-10 then has a four-level interchange with I-15 before traveling through Fontana, Rialto, and Colton. I-10 then intersects with I-215, where the San Bernardino Freeway ends, before briefly entering San Bernardino city proper and traveling through Loma Linda and Redlands. In Redlands, I-10 intersects with the SR 210 freeway (future I-210) and with SR 38 before entering Yucaipa and eventually Riverside County.

In 2019, SBCTA planned to add two more interchanges in Fontana at Beech and Alder Avenues to reduce congestion at the Sierra and Cherry avenue exits.

Riverside County

In Riverside County, I-10 goes through Calimesa before entering Beaumont and merging with the eastern end of SR 60 (itself formerly the California segment of US 60). In Banning, I-10 has a diamond intersection with SR 243 before passing through San Gorgonio Pass between the San Bernardino and San Jacinto mountains (where the vegetation makes a rapid change between Mediterranean and desert ecology) and entering Palm Springs. The next 35 miles (56 km) of the freeway, between SR 111 and Dillon Road, was named the Sonny Bono Memorial Freeway in 2002. Although I-10 intersects with the northern terminus of SR 111, the major artery to Palm Springs, it mostly bypasses the city, then connects to SR 62, a major east–west route through the Colorado Desert. I-10 cuts through Cathedral City and passes just outside the northern city limits of Rancho Mirage, Palm Desert, and La Quinta before entering Indio. I-10 then has an interchange in Coachella with the northern end of the SR 86 expressway, which also leads to SR 111.

Several miles east and roughly halfway between Indio and Blythe, in the community of Desert Center, I-10 intersects with SR 177, a turnoff that leads to Desert Center Airport and connects to SR 62. Three miles (4.8 km) south of I-10 at the Wiley's Well exit, between Desert Center and Blythe, are the Chuckawalla Valley and Ironwood state prisons. Near the Arizona state line, I-10 meets the terminus of SR 78. In the city of Blythe, I-10 runs concurrently with US 95 as both routes cross the Colorado River into Arizona.

The speed limit on the entire Riverside County segment of I-10 is 70 mph (110 km/h). I-10 westbound is usually signed as toward San Bernardino and/or Los Angeles in the Colorado Desert. Eastbound, in the San Gorgonio Pass, the signage indicates "Indio, Other Desert Cities" and indicates "Blythe" after Indio; the first sign for Phoenix does not occur until Indio.

Express lanes

There are two parts of special toll lanes along Interstate 10, one in Los Angeles County and the other in San Bernardino County.

In Los Angeles County, the El Monte Busway is a special road for buses and other vehicles. It runs along the San Bernardino Freeway between Alameda Street near Union Station in Downtown Los Angeles and a point west of I-605 in El Monte. From Alameda Street to I-710, it runs next to the freeway. After the I-710 interchange, these lanes join back with I-10. Eastbound buses stop at El Monte station before the toll lanes end west of I-605. This bus route has a hidden state name, Route 10S.

The 12.91-mile stretch of toll lanes in San Bernardino County opened in 2024, and runs between Monte Vista Avenue and Etiwanda Avenue at the Ontario–Fontana city limit.

As of January 2026, some toll rules are different between the counties. The toll lanes in Los Angeles County are part of the Metro ExpressLanes project managed by LA Metro. The ones in San Bernardino County are run by the SBCTA and use TCA as a partner. In both areas, single drivers pay a toll based on traffic levels, but cars with three or more people and motorcycles ride free. For two-person cars in Los Angeles County, they pay during busy times but not at other times; in San Bernardino County, two-person cars always pay. All tolls are collected using an electronic system, so there are no cash toll booths. Every vehicle needs a FasTrak Flex transponder to show how many people are inside. Drivers without a FasTrak tag will be charged extra.

There are plans to build a much longer network of toll lanes between Downtown Los Angeles and Redlands. This will be done in four steps. As of 2024, the part in Los Angeles County is being studied, the section from Etiwanda Avenue to Pepper Avenue in Colton will start building in 2025, and the part from Pepper Avenue to Ford Street in Redlands is still being planned.

History

What is now I-10 east of Los Angeles was part of an old road called the Atlantic and Pacific Highway. By 1926, when roads across the country got new numbers, the road east of Indio was not paved, but the road west to San Bernardino and Los Angeles was. In 1931, the road from San Bernardino to Indio became known as Legislative Route 26.

I-10 was the first freeway in Los Angeles. A four-mile section opened in 1935, connecting downtown Los Angeles to the southern San Gabriel Valley. It was called the "Air Line route" and was a big step in traffic planning.

The road east from Los Angeles became part of the Interstate Highway System in 1957 and was given the number I-10. By that time, most of the San Bernardino Freeway was finished. Over the years, other numbered roads were removed, leaving only I-10.

The part west of downtown Los Angeles was finished around 1964 and also became I-10. After an earthquake in 1994, some parts were rebuilt to be stronger.

In 2015, a bridge near Desert Center fell because of flooding from a hurricane. In 2023, a fire under a freeway in downtown Los Angeles caused damage, but the road reopened sooner than expected.

The I-10 is part of the route for the Juan Bautista de Anza National Historic Trail. Signs were added in 2005 to help drivers follow this old trail.

Exit list

Spur to US 101

The law says that Route 10 includes a short road connecting to I-5 (the Golden State Freeway) and going west to US 101 (the Santa Ana Freeway) near downtown Los Angeles. This part of the road used to be part of the San Bernardino Freeway and carried US highways long before the Golden State Freeway was built. It was once part of the Interstate Highway System but is no longer.

This road only has signs for the roads it connects to: US 101 going north and I-10 going east. It has only two places to leave the road: one right before it joins US 101 northbound, and another before it joins I-10 eastbound. You cannot go directly from this road to I-5.

Exit list
The entire route is in Los Angeles, Los Angeles County.

Related routes

California has three smaller highways connected to I-10:

• The Harbor Freeway from San Pedro to near Downtown Los Angeles is called I-110. The part continuing to Pasadena uses the old Arroyo Seco Parkway and is SR 110.
• The Foothill Freeway from Sylmar to Glendora is I-210. The rest of this road to Redlands is SR 210.
• The Long Beach Freeway from Long Beach to Monterey Park is I-710. Plans to extend it further north faced opposition, so the part built in Pasadena is secretly SR 710.

There is also a small loop road called a business loop of I-10 that goes through Blythe in Riverside County.