On February 18, 1850 California became a State of the Union and 27 counties were created. One of these was San Joaquin County. Captain Charles M. Weber was instrumental in developing the City of Stockton as the County Seat and as a Port of Entry. Today, ships still deliver cargo to the Port of Stockton by the channel Captain Weber had dug in the 1800s.

The name San Joaquin comes from Joachim and has religious significance. A Spanish lieutenant named Marago in 1813 explored the “Valle de los Tulares.” Finding a little stream that headed in the Sierra Nevadas, emptying into the Buena Vista lake, he called it San Joaquin. The rivulet christened the great river, and it in turn gave its name to the valley and county through which it ran .

The State of California today is divided into 58 counties. These are political subdivisions of the state. San Joaquin County is a General Law County. This means the county operates under the general law of the State of California.