- San Joaquin Genealogical Society | Who We Are | Join Us | Towns | Map | Publications | Links | Orders | Queries | Surnames | Notices | Welcome to our homepage San Joaquin County, California, the gateway to the mother lode during the Gold Rush in the 1850's, today is at the center of California's Central Valley farmland. If you look at the map of California, we're located almost due east of San ...www.rootsweb.com/~sjgs