San Joaquin County

County in central California; area 3,665 sq km/1,415 sq mi; population (1990) 480,600. Stockton is its capital and largest city; Lodi, Tracy, and Manteca are the other centres of an area that extends from the Coast Ranges in the southwest to the Sierra Nevada foothills in the east. A rich agricultural region, it produces a wide variety of fruits, vegetables, nuts, grains, dairy goods, and livestock.

The county is situated in the heart of the Central Valley. It includes much of the San Joaquin River delta and is crisscrossed with natural and constructed channels, especially in the northwest. It is watered by the Mokelumne, Stanislaus, and Calaveras rivers.