til 1939, the company had offices in San Francisco, California; St. Louis, Missouri; and New York City. The St. Louis office was closed in 1939, and San Francisco operations continued until 1949, when New York became the sole headquarters. Shell increased its oil exploration activities and expanded production to satisfy the growing fuel needs created by U.S. drivers' passion for big cars. New chemical plants were built that enabled Shell to become a leading producer of epoxy resins, ethylene, synthetic rubber, detergent alcohols, and other chemicals. Shell also pioneered the development of new fuel products during the 1950s, including jet fuel and high-octane, unleaded gasoline for automobiles.