I saw in a book and then ran to verify in Wikipedia.
https://en.wikipedia.org/wiki/History_of_oil_in_California_through_1930:
The story of oil production in California began in the late 19th century. In 1903, California became the leading oil-producing state in the US, and traded the number one position back-and forth with Oklahoma through the year 1930. As of 2012, California was the nation's third most prolific oil-producing state, behind only Texas and North Dakota. In the past century, California's oil industry grew to become the state's number one GDP export and one of the most profitable industries in the region.
The first question this brings to me is how did California avoid the resource curse? (To my non-technical outsider's view, Texas, Oklahoma, and North Dakota haven't since they don't tend to invest in their citizens -- but just writing this out is clarifying for me how muddled my thoughts on this matter are).
While at the Wiki, this is cool:
Native Americans were keenly aware of oil reserves in California, and they relied on its utility for thousands of years, albeit not for energy sources. The most abundant oil seep in the ancient California territory was the La Brea tar pits, in present-day Los Angeles. Native Americans used oil from La Brea and other seeps primarily as a lubricant, but they also used it as a sealant to waterproof canoes. When Spanish explorers arrived in California in the 1500s, they also used oil to seal cracks in their ships and the roofs of their homes.
