Since 1956, United States Auto Club (USAC Racing) has proven itself as being the most diversified motorsports sanctioning body in the world. It is the official sanctioning body of many of today’s largest racing series including its own suite of circle track series in Silver Crown, Sprint, Midget and .25 Midget racing, SRO World Challenge, Porsche Sprint Challenge, NRX Rallycross, American Rally Association, International Snowmobile Racing, Robby Gordon Stadium Trucks, Ultra 4 Racing, Red Bull Scramble Series and USAC Karting. USAC has over 20,000 competitors racing at more than 1,000 sanctioned events globally.