List of Interstate Highways in California

Interstate Highways in California
Highway shields for I-5, I-580, and I-80 Bus. Loop
Interstate Highways highlighted in red; related state routes in purple
System information
Maintained by Caltrans
Length	2,466.744 mi (3,969.840 km)
Highway names
Interstates	Interstate XX (I-XX)
Business Loop	Interstate XX Business Loop (I-XX Bus.)
System links
State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways

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^[1][2]) 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.