The United States Auto Club (USAC) was formed in 1956 by Indianapolis Motor Speedway owner Tony Hulman. USAC is one of the oldest and most prestigious sanctioning bodies of auto racing in the United States. From 1956 to 1979, the USAC sanctioned the United States National Championship, and from 1956 to 1997 the organization sanctioned the Indianapolis 500. It is the official sanctioning body of many of today’s largest racing series including its own suite of circle track series in Sprint, Silver Crown, Midget, Micro and .25 Midget racing (quarter midgets), Porsche Sprint Challenge North America, Pirelli World Challenge, American Rally Association, International Snowmobile Racing, Robby Gordon Stadium Trucks, Radical Racing, Ultra 4 Racing, Formula Race Promotions and Karting. USAC has over 25,000 competitors racing at more than 500 sanctioned events globally.