Gulf Oil grew steadily in the inter-war years, with its activities mainly confined to the United States. The company was characterized by its vertically integrated business activities, and was active across the whole spectrum of the oil industry: exploration, production, transport, refining and marketing. It also involved itself in associated industries such as petrochemicals and automobile component manufacturing. It introduced significant commercial and technical innovations, including the first drive-in service station (1913), complimentary road maps, drilling over water at Ferry Lake, and the catalytic cracking refining process (Gulf installed the world's first commercial catalytic cracking unit at its Port Arthur, Texas, refinery complex in 1951). Gulf also established the model for the integrated, international "oil major", which refers to one of a group of very large companies that assumed influential and sensitive positions in the countries in which they operated. In 1924 had acquired the Venezuelan-American Creole Syndicate's leases in the strip of shallow water 1.5 kilometres (0.93 mi) wide along the Lake Maracaibo east shore.