Soon Kern River production accounted for 7 out of every 10 barrels of oil that came from California .
Kern River field by 1903 had made California the top oil - producing state in the country .
Soon Kern River production accounted for 7 out of every 10 barrels of oil that came from California , and Kern River field by 1903 had made California the top oil - producing state in the country .