The USGS Central Region Energy Team assesses oil and gas resources of the United States. The onshore and State water areas of the United States comprise 71 provinces. Within these provinces, Total Petroleum Systems are defined and Assessment Units are defined and assessed. Each of these provinces is defined geologically, and most province boundaries are defined by major geologic changes.
The San Joaquin Basin Province is located in south-central California, encompassing all or parts of Fresno, Kern, Kings, Madera, Merced, Monterey, San Benito, San Luis Obispo, Stanislaus, and Tulare counties. The main population centers within the study area are Bakersfield, Fresno, and Modesto. The province boundary was drawn to include the geologic structures generally considered to be in or bounding the San Joaquin Basin Province.