During the late 19th cent., many of the modern oil companies were created: John D. Rockefeller invested in a Cleveland oil refinery during the Civil War and in 1870 created Standard Oil, which refined about 95% of the United States' oil in 1880. In 1911, Standard Oil was declared an illegal monopoly and split into 34 companies, including Esso (renamed Exxon in 1972), Mobil, Chevron, Atlantic Richfield (later ARCO), and Amoco. Texaco (founded in 1902), Shell (1907), and British Petroleum (1909) were also established in this period. As the auto industry vastly increased the demand for gasoline refined from oil, oil companies expanded their search for new reserves. In the 1930s oil companies began exploiting a huge E Texas oil field that would eventually produce 4 billion barrels of oil. Chevron, Texaco, Exxon, and Mobil expanded their reserves by purchasing the rights to the extensive Saudi Arabian oil fields for only $50,000. In 1946 oil replaced coal as the world's most popular energy source.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.