Page "California Department of Transportation" Paragraph 11

For administrative purposes, Caltrans has divided the state of California into 12 districts supervised by district offices.

Most districts cover multiple counties ; District 12 ( Orange County ) is the only district with one county.

The largest districts by population are District 4 ( San Francisco Bay Area ) and District 7 ( Los Angeles and Ventura counties ).

Like most state agencies, Caltrans maintains its headquarters in Sacramento, which is covered by District 3.