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.