The 21st season of the ProKart Challenge concluded this past October, completing the five events with six rounds of competition for the Superkarts! USA regional program. Eleven different class champions were crowned following the action at the K1 Circuit finale event.

The California ProKart Challenge hosted the penultimate round of the 2021 season on the September 11-12 weekend at the Willow Springs International Raceway. The Rosamond, California facility has been the site of many Superkarts! USA regional program events in the past, including both the famed Streets of Willow course and the karting circuit. The two-day event for Round Five of the 2021 championship program was held on the nine-turn, 6/10-mile kart track in the counter-clockwise direction.