| Field | Value |
|---|
| title | Interstate Highways in California |
| shields | |
| caption | Highway shields for I-5, I-580, and I-80 Bus. Loop |
| maint | Caltrans |
| map | |
| map_custom | yes |
| map_notes | Interstate Highways highlighted in red; related state routes in purple |
| length_mi | 2466.744 |
| length_round | 0 |
| interstate | Interstate XX (I-XX) |
| label1 | Business Loop |
| field1 | Interstate XX Business Loop (I-XX Bus.) |
| links | CA |
This is a list of Interstate Highways in the U.S. state of California that have existed since the 1964 renumbering. It includes routes defined by the California State Legislature 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
- U.S. Routes and state highways that traverse California are also defined in the California Streets and Highways code as state routes. This list does not include these state routes as they are listed separately.
- A few cases exist, such as I-110, where a defined California State Route partially overlaps with a federally defined Interstate Highway, while the remaining portion is signed as a state highway. This table only addresses the portion signed as an Interstate in these cases.
- One Interstate Highway—I-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 in California.
- Conversely, a few segments exist that are not part of a federally defined Interstate Highway but are still signed as such by Caltrans. Examples include I-80's westernmost segment between US 101 and the Bay Bridge.
- Lengths for each state route were initially measured as they existed during the 1964 state highway renumbering (or during the year the route was established, if after 1964), and do not necessarily reflect the current mileage.
- The years listed reflect when the route was affected by legislative action, this is not necessarily the same year as the actual construction or signing changes to the route.
- Concurrencies 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. Furthermore, Caltrans may not sign all concurrencies, and instead may only post the highway shields for the route with the contiguous segment in the code.
- Some highways are not contiguous as the state has relinquished control of small sections to local governments. The stated length of the highway may or may not reflect the portions under local control.
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
File:Wind farm from Interstate 10.jpg|alt=Photograph|I-10 eastbound with the San Gorgonio Pass wind farm in the background
File:Interstate15 Ivanpah Valley.jpg|alt=Photograph|I-15 northbound descending into the Ivanpah Valley 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
File:The 405 in the Sepulveda Pass.JPG|alt=Photograph|Cars driving on I-405 through the Sepulveda Pass
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
Interstate business routes in California are assigned by the California Department of Transportation (Caltrans), but are not maintained by Caltrans unless they overlay other routes of the state highway system. Local authorities may request route assignment from the Caltrans Transportation System Information Program, and all requests require approval of the executive committee of the American Association of State Highway and Transportation Officials (AASHTO).