Valero Energy Corporation Headquarters, Texas

San Antonio-based Valero is the largest refiner in the USA, with fourteen refineries, six of which are in Texas: at Corpus Christi, Houston, Port Arthur, Texas City, McKee, and Three Rivers. It is also one of the nation's largest gasoline resellers, selling its products under the Diamond Shamrock, Ultramar, Valero, and Beacon brands at over 5,000 outlets. Valero is a relatively new company, created out of the Coastal States Gas Corporation, as part of litigation settled in 1980. It has no upstream operations.