The term 'Western Gas Chain' refers to ARCO, a major American gas station chain. ARCO stands for Atlantic Richfield Company and is headquartered in La Palma, California. It is the largest company-owned convenience store chain in the United States and operates more than 1, 500 locations in California, Oregon, Washington, Nevada, Arizona, and Idaho. ARCO also offers a variety of services, including car washes, auto repair, and food service.