This is a list of

Interstate Highways The Dwight D. Eisenhower National System of Interstate and Defense Highways, commonly known as the Interstate Highway System, is a network of controlled-access highways that forms part of the National Highway System in the United States. Th ...

in the U.S. state of California that have existed since the 1964 renumbering. It includes routes defined by the

California State Legislature The California State Legislature is a bicameral state legislature consisting of a lower house, the California State Assembly, with 80 members; and an upper house, the California State Senate, with 40 members. Both houses of the Legisla ...

but never built, as well as routes entirely relinquished to local governments. Each state highway in California is maintained by the California Department of Transportation (Caltrans) and is assigned a ''Route'' (officially ''State Highway Route'') number in the Streets and Highways Code (Sections 300-635). Under the code, the state assigns a unique ''Route X'' to each highway and does not differentiate between state, US, or Interstate highways.

Overview

Lengths for each state route were initially measured as they were during the 1964 state highway renumbering (or during the year the route was established, if after 1964) based alignment that existed at the time, and do not necessarily reflect the current mileage. Portions of some routes have been relinquished to or are otherwise maintained by local or other governments, and may not be included in the length listed below. Several routes are broken into non-contiguous pieces, and their lengths may not reflect the overlaps that would be required to make them continuous. Some routes may also have a gap because it is either explicitly defined in the California Streets and Highways Code or due to an unconstructed portion, and the listed length may or may not reflect the gap. Additionally, if a route was renumbered, the old or new number is given in the "notes" column. Years shown are when legislative action was taken, not when real-world changes were made. Concurrences are not explicitly codified in the Streets and Highways Code; such highway segments are listed on only one of the corresponding legislative route numbers—for example, the I-80/ I-580 concurrency, known as the Eastshore Freeway, is only listed under Route 80 in the highway code while the definition of Route 580 is broken into non-contiguous segments. When a highway is broken into such segments, the total length recorded by Caltrans only reflects those non-contiguous segments, and does not include those overlaps that would be required to make the route continuous. Since the 1990s, a number of piecemeal relinquishments have been made. These are generally reflected in the length but not the termini. Former termini are not shown if they are along the current route, meaning that the route was simply extended. One Interstate Highway— Interstate 305—is defined only federally; the state calls it part of US 50. It was signed as part of Business Interstate 80, the only state-maintained

Interstate business route The Interstate Highway System of the United States, in addition to being a network of freeways, also includes a number of Business Routes assigned by the American Association of State Highway and Transportation Officials (AASHTO). These routes con ...

in California.

Primary Interstates

File:I-5 near Shasta.jpg, alt=Photograph, I-5 southbound approaching Mount Shasta File:I-8 Alpine.jpg, alt=Photograph, I-8 in

Alpine Alpine may refer to any mountainous region. It may also refer to: Places Europe * Alps, a European mountain range ** Alpine states, which overlap with the European range Australia * Alpine, New South Wales, a Northern Village * Alpine National Pa ...

File:Wind farm from Interstate 10.jpg, alt=Photograph, I-10 eastbound with the

San Gorgonio Pass wind farm The San Gorgonio Pass wind farm is a wind farm that stretches from the eastern slope of the San Gorgonio Pass, near Cabazon, to North Palm Springs, on the western end of the Coachella Valley, in Riverside County, California. Flanked by Mount San ...

in the background File:Interstate15 Ivanpah Valley.jpg, alt=Photograph, I-15 northbound descending into the

Ivanpah Valley The Ivanpah Valley is in southeastern California and southern Nevada in the United States. The valley is between the New York Mountains and the Ivanpah Mountains in San Bernardino County on the California side, and in Clark County on the Nevada ...

towards Primm, Nevada at the California-Nevada state line File:Interstate 40 in Fenner Valley 1.jpg, alt=Photograph, I-40 eastbound near Fenner File:I80Donnersummit.JPG, alt=Photograph, I-80 eastbound in the Sierra Nevada from the Yuba Gap overpass towards the western approach to Donner Summit

Auxiliary Interstates

File:Sep 09 215 Construction.jpg, alt=Photograph, Construction on I-215 between Inland Center Drive and Orange Show Road in San Bernardino File:Interstate 280 near Stanford p1130161.jpg, alt=Photograph, I-280 running along near

Stanford University Stanford University, officially Leland Stanford Junior University, is a private research university in Stanford, California. The campus occupies , among the largest in the United States, and enrolls over 17,000 students. Stanford is consider ...

File:The 405 in the Sepulveda Pass.JPG, alt=Photograph, Cars driving on I-405 through the

Sepulveda Pass Sepulveda Pass (elevation ) is a low mountain pass through the Santa Monica Mountains in Los Angeles. It is named after the Sepúlveda family of California, a prominent Californio family that owned the land where the pass lies. It connects the L ...

File:Kluft-Photo-Aerial-I580-Altamont-Pass-Img 0037.jpg, alt=Photograph, I-580 winding through the Altamont Pass wind farm File:I605 CA dv 26 north lg.jpg, alt=Photograph, I-605 northbound approaching its northern terminus with I-210 File:View from I-680 (2).jpg, alt=Photograph, I-680 northbound descending from Mission Pass File:Empty Freeway.jpg, alt=Photograph, An empty I-805 at its interchange with I-8 in San Diego's Mission Valley File:Harborfreeway2.jpg, Rush hour on I-110 in Los Angeles

Business Routes

Notes

References