California Code, Elections Code - ELEC § 10400

Whenever two or more elections, including bond elections, of any legislative or congressional district, public district, city, county or other political subdivision are called to be held on the same day, in the same territory, or in territory that is in part the same, they may be consolidated pursuant to this chapter upon the order of the governing body or bodies or officer or officers calling the elections.

The elections, whether held under a freeholder charter or under any state law, or both, may be consolidated, and different elections called by the same governing body may be consolidated.