County in California
San Joaquin County officially the County of San Joaquin is a county in the U.S. state of California. As of the 2010 census, the population was 685,306. The county seat is Stockton.
San Joaquin County comprises the Stockton–Lodi–Tracy metropolitan statistical area within the regional San Jose–San Francisco–Oakland combined statistical area. The county is located in Northern California’s Central Valley just east of the very highly populated nine-county San Francisco Bay Area region and is separated from the Bay Area by the Diablo Range of low mountains with its Altamont Pass.