The United States Auto Club (USAC) is one of the sanctioning bodies of auto racing in the United States. From 1956 to 1979, USAC sanctioned the United States National Championship, and from 1956 to 1997 the organization sanctioned the Indianapolis 500. Today, USAC serves as the sanctioning body for a number of racing series, including the Silver Crown Series, National Sprint Cars, National Midgets, Speed2 Midget Series, .25 Midget Series, Stadium Super Trucks, TORC: The Off-Road Championship, and Pirelli World Challenge. Beginning in 1971, all dirt races were split from the National Championship. From 1971 to 1980, the series was named National Dirt Car Championship, then renamed Silver Crown Series in 1981.
At first glance, the appearance of a Silver Crown Car is somewhat similar to a Sprint Car. However, Silver Crown cars are much larger and carry approximately 75 gallons of fuel, alcohol, versus about 22 gallons for a Sprint Car. They also have a longer wheelbase, approximately 96 inches compared for Sprint. They have the option of an on-board starter (like a car), or a starter that was not attatched to the car, i.e. aircraft style starter that was shoved into the front of the car. Two way radios are allowed in a Silver Crown car (but not Sprint car. Weight minimum of 1475 pounds without the driver, vs 1175 pounds without driver on Sprint Car.