San Joaquin County features an international deep-water port and good highway system. Population density is high because this area is providing additional and more affordable housing to the greater San Francisco area. About 745,000 people live in San Joaquin County. Median household income is $53,250, and the median home value is $365,000. The county seat of the county is Stockton.

San Joaquin County is located in California’s Central Valley, east of San Francisco. San Joaquin's area is 1,426 square miles. Due to its low inland elevation and runoff from the Sierra Nevada, much of the county is a marshy delta.

San Joaquin County was one of the original United States counties of California, created in 1850 at the time of statehood. The county was named for the San Joaquin River which runs through it.