The California oil and gas industry has been a major industry for over a century. Oil production was a minor factor in the 19th century, with kerosene replacing whale oil and lubricants becoming essential to the machine age. Oil became a major California industry in the 20th century with the discovery on new fields around Los Angeles and the San Joaquin Valley, and the dramatic increase in demand for gasoline to fuel automobiles and trucks. In 1900 California pumped 4 million barrels, nearly 5% of the national supply. Then came a series of major discoveries, and the state pumped 100,000,000 barrels in 1914, or 38% of the national supply. In 2012 California produced 197 million barrels of crude oil, out of the total 2,375 million barrels of oil produced in the U.S. California drilling opera