USAC initially tried to ban all CART drivers from the 1979 Indianapolis 500, informing CART teams by telegram during their event at Atlanta Motor Speedway, until CART succeeded in obtaining an injunction to allow its cars to qualify. Of the 20 races held in 1979, 13 were part of the 1979 CART Championship. An attempt by USAC and CART to jointly sanction races in 1980 as the Championship Racing League saw USAC withdraw after 5 races, and by the end of 1981 the only USAC sanctioned asphalt championship race was the Indianapolis 500.