Racing resumed in full in 1946. The 1946 season is unique, in that it included six Champ Car events, and 71 "Big Car" races, as organizers were initially unsure about the availability of cars and participation. AAA ceased participation in auto racing at the end of the 1955 season. It cited a series of high-profile fatal accidents, namely Bill Vukovich at Indianapolis, and the Le Mans disaster. Through 1922 and again from 1930 to 1937, it was commonplace for the cars to be two-seaters, as opposed to the aforementioned standard single-seat form. The driver would be accompanied by a riding mechanic (or "mechanician"). USAC (1956–1978) The national championship was taken over by the United States Auto Club (USAC), a new sanctioning body formed by the then-owner of the Indianapolis Motor Speedway, Tony Hulman. Championship racing continued to grow in popularity in a stabilized environment for over two decades, with the two traditional disciplines of paved oval tracks and dirt oval tracks. During the 1950s, front-engined "roadsters" became the dominant cars on the paved oval tracks, while "upright" Champ Dirt Cars continued to dominate on dirt tracks. In the 1960s, drivers and team owners with road racing backgrounds, both American and foreign, began creeping into the series and the paved oval track cars evolved from front-engine "roadsters" to rear-engine formula-style racers. Technology, speed, and expense climbed at a rapid rate. The schedule continued to be dominated by oval tracks, but a few road course races were added to assuage the newcomers. Dirt tracks were dropped from the national championship after 1970. During the 1970s, the increasing costs began to drive some of the traditional USAC car owners out of the sport. The dominant teams became Penske, Patrick, Gurney, and McLaren, all run by people with road racing backgrounds. There was a growing dissent between these teams and USAC management. Events outside Indianapolis were suffering from low attendance, and poor promotion. The Indy 500 was televised on a same day tape delayed basis on ABC, however, most of the other races had little or no coverage on television. Towards the end of the decade, the growing dissent prompted several car owners to consider creating a new sanctioning body to conduct the races. Meanwhile, two events had a concomitant effect on the situation. Tony Hulman, president of the Indianapolis Motor Speedway and founder of USAC, died in the fall of 1977. A few