Effective U.S. control continued even after the end of the occupation of Japan as a whole in 1952. The United States dollar was the official currency used, and cars drove on the right, American-style, as opposed to on the left as in Japan. The islands switched to driving on the left in 1978, six years after they were returned to Japanese control. The U.S. used their time as occupiers to build large army, air force, navy, and marine bases on Okinawa.