Marathon Corporate Headquarters, Texas

Marathon, based in Houston, is the fourth largest U.S.-based integrated oil and gas company, after ExxonMobil, Chevron, and ConocoPhillips. Founded as the Ohio Oil Company in 1887, it grew by acquiring other oil and pipeline companies, and by expanding its operations into West Texas, Alaska, Canada, Libya, Gabon, Iraq, and elsewhere. Marathon has also been invovled in developing both the Eagle Ford and the Bakken shale oil plays. It took the Marathon name in 1962, and moved its headquarters to Houston in 1990. Its revenue in 2013 was $14 billion.