San Joaquin is one of the 58 counties in the state of California. It was created in 1850, making it one of the original counties of the state. As of the 2010 census the population was 685,306, up from 563,598 in 2000. The county seat and largest city is Stockton. The county has 1,426.25 (3,694.0 km2) square miles of area, of which 1,399.28 sq mi (3,624.1 km2) is land. It is bordered by Sacramento County on the north, Amador County to the northeast, Calaveras County to the east, Stanislaus County to the south, Santa Clara County to the southwest, and Alameda and Contra Costa counties to the west.