The 1978 USAC Championship Car season consisted of 18 races, beginning at Phoenix on March 18 and concluding at the same location on October 28. The USAC National Champion was Tom Sneva and the Indianapolis 500 winner was Al Unser. This was the last year before the first USAC/CART "Split". By winning the Indianapolis 500, Pocono 500, and California 500, Al Unser swept the Indy car "Triple Crown", the only driver in history to do so.