Exxon Mobile, Chevron and ConocoPhillips are three of the top American-owned oil companies based on market value, as of 2015, says Statista. Anadarko Petroleum, Valero Energy and Marathon Petroleum also rank among the top American-owned oil companies, as do Eog Resources, Occidental Petroleum and Devon Energy.
America's largest oil companies engage in refinery, drilling and exploration, according to Anadarko. Texas, California, New Mexico, North Dakota and Alaska are among the top five states where American-owned companies drill for oil, states USA Today. Large American oil companies locate their headquarters in the United States, but they typically have global operations in locations such as South America, Africa and the South Pacific.
Large oil companies are publicly traded and are not owned by individuals, according to Energy Tomorrow. As a result, many Americans own a piece of the country's largest oil companies, because oil stocks are included in many mutual funds. In addition, many individual retirement accounts are invested in oil and other energy stocks. American oil companies import oil from various countries and blend it with oil drilled in the United States, states FactCheck.org. As such, it is impossible to buy petroleum that only contains oil drilled in the United States.