The Superkarts! USA (SKUSA) was formed in 1993 to sanction races by "shifter" karts. Shifter karts are karts equiped with up to a 125cc motocross engine/gearbock assembly with 6 speeds and upto 40 hp. These karts can trace thier roots back to the early racing karts of the 1950's.

SKUSA has three tiers of racing: National Pro Racing, Regional Pro Racing, and Special Pro Events. The Regional Pro Series is broken up into 21 separate regions that stretch from Alaska to Hawaii, including Canada and Mexico. Each region has their own series of races.

National Pro Racing has the Pro Moto Tour that was established in 1998. This 7 race series is held from May through September, with the series winner collecting the #1 plate for the next season.

In addition to the Pro Moto Series, SKUSA presents several National Special Events. These include the "Long Track Nationals", the "US Amateur Championships", the "King of the Streets", and the "SuperNationals".