San Joaquin is a city in Fresno County, California, United States. The population was 3,270 at the 2000 census. The nearest high school in the area is Tranquillity High School in Tranquillity, CA. San Joaquin apartments for rent comparison page shows most up to date rent information on San Joaquin apartments and houses. Rent information is obtained from multiple rental sources but we cannot guarantee their accuracy.