California state highway system

Standard route signage in California
System information
Notes:	All classes of state-numbered highways are generally state-maintained.
Highway names
Interstates:	Interstate X (I-X)
US Highways:	U.S. Route X (US X)
State:	State Route X (SR X)
System links
State highways in California Interstate U.S. State Pre-1964 History Unconstructed Deleted Freeway Scenic

The state highway system of the U.S. state of California is a network of highways that are owned and maintained by the Highway Division of the California Department of Transportation (Caltrans).

Each highway is assigned a Route (officially State Highway Route) number in the . Most of these are numbered in a statewide system, and are known as State Route X (abbreviated SR X). United States Numbered Highways are labeled US X, and Interstate Highways are Interstate X. Under the code, the state assigns a unique Route X to each highway, and does not differentiate between state, US, or Interstate highways.

The California Highway Patrol (CHP) is tasked with patrolling all state highways to enforce traffic laws.

California's highway system is governed under the state's Streets and Highways Code. Since July 1 of 1964, the majority of legislative route numbers, those defined in the Streets and Highways Code, match the sign route numbers. For example, Interstate 5 is listed as "Route 5" in the code.

On the other hand, some short routes are instead signed as parts of other routes — for instance, Route 112 and Route 260 are signed as part of the longer State Route 61, and Route 51 is part of Interstate 80 Business.

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.