Mendocino Oil Co. - 1864 dated California Oil Stock Certificate - Bottom Left Tear through Design

Stock printed by Towne & Bacon, Printers, S.F. with 25 cents Washington revenue stamp! Civil War era dated! Bottom left tear through design.

The oil and gas sector in California has played a significant role in the economic and cultural landscape of the state for more than a century. In the 19th century, oil production was relatively minor, as kerosene began to replace whale oil and lubricants became vital for the burgeoning machine age. However, the 20th century marked the emergence of oil as a dominant industry in California, particularly following the discovery of new oil fields in the vicinity of Los Angeles and the San Joaquin Valley, alongside a substantial rise in gasoline demand to power automobiles and trucks. By the year 1900, California was producing 4 million barrels (640,000 m³) of oil, accounting for nearly 5% of the total national output.

Following the year 1848, prospectors identified a growing number of oil seeps—natural occurrences where oil rises to the surface. In Northern California, oil seeps were located in Humboldt, Colusa, Santa Clara, and San Mateo Counties, as well as in the asphaltum seeps and bituminous residues found in Mendocino, Marin, Contra Costa, Santa Clara, and Santa Cruz Counties. In Southern California, significant seeps were discovered in Ventura, Santa Barbara, Kern, and Los Angeles Counties. The interest in oil and gas seeps gained momentum during the 1850s and 1860s, particularly after the commercial discovery of oil in Pennsylvania in 1859, which sparked widespread enthusiasm.