Interstate 10 in California
Interstate 10 is a transcontinental Interstate Highway in the United States, stretching from Santa Monica, California, to Jacksonville, Florida. The segment of I-10 in California, also known as the Pearl Harbor Memorial Highway, runs east from Santa Monica through Los Angeles, San Bernardino, and Palm Springs before crossing into the state of Arizona. In the Greater Los Angeles area, it is known as the Santa Monica and San Bernardino freeways, linked by a short concurrency on I-5 at the East Los Angeles Interchange. I-10 also has parts designated as the Rosa Parks and Sonny Bono Memorial freeways. Some parts were also formerly designated as the Christopher Columbus Transcontinental Highway. However, the California State Legislature removed this designation following the passage of a bill on August 31, 2022. I-10 is also known colloquially as "the 10" to Southern California residents.
Route description
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:Route 1 in Santa Monica to Route 5 near Seventh Street in Los Angeles.
Route 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 '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 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 and San Diego 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
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. 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 from the Harbor Freeway interchange to the Arlington Avenue offramp. Most of these lanes are full at peak travel times. 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.
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.
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 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 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. 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 and entering Palm Springs. The next 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. 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. 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 sections of high-occupancy toll lanes along I-10, one in Los Angeles County and the other in San Bernardino County.In Los Angeles County, the El Monte Busway is a grade-separated, shared-use HOT and express bus corridor running 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, the El Monte Busway runs parallel to the north side of the freeway. After the I-710 interchange, these lanes merge back to the median of I-10. Eastbound busses exit at El Monte station in El Monte before the HOT lanes for other vehicles end west of I-605. The entire bus route of the El Monte Busway between Alameda Street and El Monte station's bus entrance at Santa Anita Avenue carries the hidden state designation of Route 10S.
The segment of HOT lanes in San Bernardino County opened in 2024, and runs between Monte Vista Avenue and Etiwanda Avenue at the Ontario–Fontana city limit.
, some toll polices differ between the counties. The HOT lanes in Los Angeles County are part of the Metro ExpressLanes project administered by the Los Angeles County Metropolitan Transportation Authority. The ones in San Bernardino County, branded as the San Bernardino Express Lanes, are operated by the San Bernardino County Transportation Authority and use Transportation Corridor Agencies as the processing partner. In both segments, solo drivers are tolled using a congestion pricing system based on the real-time levels of traffic. Carpools with three or more people and motorcycles are not charged. For two-person carpools using the Los Angeles County segment, they are charged the posted toll during the peak hours between 5:00 am and 9:00 am, and between 4:00 pm and 7:00 pm; no toll is charged during off-peak hours. Two-person carpools using the San Bernardino County segment do not receive any discount. All tolls are collected using an open road tolling system, and therefore there are no toll booths to receive cash. Each vehicle using the HOT lanes is required to carry a FasTrak Flex transponder with its switch set to indicate the number of the vehicle's occupants. Solo drivers may also use the FasTrak standard tag without the switch.
Drivers without any FasTrak tag will be assessed a toll violation regardless of whether they qualified for free. For those violators on the San Bernardino County segment, they will get TCA's benefit of being able to pay online 5 days after their trip without an additional toll violation penalty.
There are longer-term plans to have a continuous HOT lanes network between Alameda Street in Downtown Los Angeles and Ford Street in Redlands. This expansion is planned in four phases., the proposed segment in Los Angeles County to convert the new HOV lanes to HOT lanes and bridge the gap between I-605 and Monte Vista Avenue is under environmental review, the section from Etiwanda Avenue to Pepper Avenue in Colton is planned to break ground in 2025, and the segment from Pepper Avenue to Ford Street in Redlands is still in the planning stage.