California's 13th State Assembly district is one of 80 California State Assembly districts.

It is currently represented by Democrat Rhodesia Ransom of Tracy.

The district consists of western San Joaquin County, including the southeastern quarter of the Sacramento–San Joaquin River Delta.

The district is a major gateway between the rest of the Central Valley and the San Francisco Bay Area.

Due to redistricting, the 13th district has been moved around different parts of the state.