State Route 23 (SR 23) is a

state highway A state highway, state road, or state route (and the equivalent provincial highway, provincial road, or provincial route) is usually a road that is either Route number, numbered or maintained by a sub-national state or province. A road numbered ...

in the

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California California () is a U.S. state, state in the Western United States that lies on the West Coast of the United States, Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares Mexico–United States border, an ...

that connects the Pacific coast and the

Santa Monica Mountains The Santa Monica Mountains are a coastal mountain range in Southern California, next to the Pacific Ocean. It is part of the Transverse Ranges. The Santa Monica Mountains National Recreation Area encompasses this mountain range. Because of its p ...

to the Conejo and Santa Clara River valleys. It runs from Pacific Coast Highway ( State Route 1) in Malibu in

Los Angeles County Los Angeles County, officially the County of Los Angeles and sometimes abbreviated as LA County, is the most populous county in the United States, with 9,663,345 residents estimated in 2023. Its population is greater than that of 40 individua ...

to Ventura Street ( State Route 126) in Fillmore in

Ventura County Ventura County () is a county located in the southern part of the U.S. state of California. As of the 2020 census, the population was 843,843. The largest city is Oxnard, and the county seat is the city of Ventura. Ventura County comprises ...

Route description

SR 23 consists of three distinct sections. The southern section begins as Decker Canyon Road near Trancas in Malibu, where SR 23 intersects with the Pacific Coast Highway (State Route 1), or "PCH." This portion provides numerous vistas of the

and the Pacific Ocean during the daytime, but extreme caution is advised, especially as the road nears PCH. It is a notoriously dangerous road, and the rusted chassis of cars that have gone over the side can still be seen. Philip Taylor Kramer, bassist with the rock band

Iron Butterfly Iron Butterfly was an American rock band formed in San Diego, California, in 1966. They are best known for the 1968 hit " In-A-Gadda-Da-Vida", providing a dramatic sound that led the way towards the development of hard rock and heavy metal m ...

from 1974–1977, allegedly committed suicide by driving his van over the side along this route. Along its steep and winding path through the

as an increasingly tight and twisting canyon road until its intersection with Potrero Road, SR 23 becomes Westlake Boulevard, where it departs

for

and heads roughly two miles northeast through the Westlake section of

Thousand Oaks Thousand Oaks is the second-largest city in Ventura County, California, located in the northwestern part of Greater Los Angeles. Approximately from the city of Los Angeles and from Downtown Los Angeles, it is named after the many oak trees pr ...

, a developed residential community. SR 23 then merges with Ventura Freeway (U.S. Route 101) and runs concurrently with it north to the Moorpark Freeway. The middle section is a major route for traffic headed between Thousand Oaks and Moorpark. It starts in Thousand Oaks, splitting off from the concurrency with US 101 and heading north, with three lanes in both directions. This section terminates at the exit for Los Angeles Avenue when the freeway turns east to become the Ronald Reagan Freeway (State Route 118). Funding for widening of the freeway was approved August 18, 2005, with construction to begin in February 2006, to be completed in 2009. The widening was completed ahead of schedule in April 2008. However, traffic along this freeway during

rush hour A rush hour (American English, British English) or peak hour (Australian English, Indian English) is a part of the day during which traffic congestion on roads and crowding on public transport is at its highest. Normally, this happens twice e ...

is extremely congested, particularly near the interchange with US 101. The northernmost section begins at State Route 118 in Moorpark (called ''Los Angeles Avenue'' in Moorpark), and heads north as Grimes Canyon Road through orange groves and sandstone cliffs. In Fillmore, it terminates at State Route 126. The road in Fillmore actually continues past Route 126 up to the foot of the

Los Padres National Forest Los Padres National Forest is a United States national forest in Southern California, southern and central California. Administered by the United States Forest Service, Los Padres includes most of the mountainous land along the California coast ...

. On SR 23 from Tierra Rejada Road to Olsen Road (and vice versa) is a bike lane. After crossing Tierra Rejada Road (going north) and Olsen Road (going south), bicyclists are prohibited from crossing. SR 23 is part of the

California Freeway and Expressway System The California Freeway and Expressway System is a system of existing or planned freeways and expressways in the U.S. state of California. It encompasses both state highways and federal highways in California. It was defined by Article 2 (comme ...

, and the freeway portion 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

Federal Highway Administration The Federal Highway Administration (FHWA) is a division of the United States Department of Transportation that specializes in highway transportation. The agency's major activities are grouped into two programs, the Federal-aid Highway Program a ...

. SR 23 is known as the Military Intelligence Service Memorial Highway from US 101 to California Route 118, in honor of the

Military Intelligence Service The Military Intelligence Service (, ''America Rikugun Jōhōbu'') was a World War II U.S. military unit consisting of two branches, the Japanese American unit (described here) and the German-Austrian unit based at Camp Ritchie, best known as ...

, the 100th Infantry Battalion, and the

442nd Regimental Combat Team The 442nd Infantry Regiment was an infantry regiment of the United States Army. The regiment including the 100th Infantry Battalion is best known as the most decorated unit in U.S. military history, and as a fighting unit composed almost ent ...

, composed entirely of

Japanese American are Americans of Japanese ancestry. Japanese Americans were among the three largest Asian Americans, Asian American ethnic communities during the 20th century; but, according to the 2000 United States census, 2000 census, they have declined in ...

History

State Route 23 has been designated as such since 1934. However, at this time it was also designated as Legislative Route 155. The freeway portion of SR 23 opened in several phases between 1971 and 1994. Before then, SR 23 ran along Moorpark Road and intersected with U.S. 101 near Newbury Park, although it still ran concurrently with U.S. 101, which was then an expressway. SR 23 was designated as part of the Freeway and Expressway System in 1959.

Decker Freeway

The Decker Freeway was an unbuilt north–south freeway that would connect SR 118,

US 101 U.S. Route 101, or U.S. Highway 101 (US 101), is a major north–south highway that traverses the states of California, Oregon, and Washington on the West Coast of the United States. It is part of the United States Numbered Highway Syst ...

, and SR 1. The freeway was part of a 1958 plan by the Metropolitan Engineering Board,1958 map
cahighways.org but was later considered to be geographically improbable and the plans were abandoned.
The freeway's southern portion, from SR 1 to US 101, follows the general alignment of Decker Canyon Road and Westlake Boulevard, a segment of SR 23. It would continue north before terminating at SR 118 near First Street.

Major intersections

References

External links