SKUSA which stands for Super Karts USA is the world of American kart racing, Superkarts! USA is the outright leader in the shifterkart category and a dedicated supporter of TaG sprint competition, presenting both regional and national events that all lead up to the program's crown jewel, the annual SuperNationals. the world of American kart racing, Superkarts! USA is the outright leader in the shifterkart category and a dedicated supporter of TaG sprint competition, presenting both regional and national events that all lead up to the program's crown jewel, the annual SuperNationals.