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.

The California ProKart Challenge began the second half of the 2019 championship season, hosting Round Four at the Marina Airport Kart Track on July 13-14. The Superkarts! USA regional program took to the home of the Monterey Bay Karters for the two-day event, with practice and qualifying held Saturday, Prefinal and Final held on Sunday. The weather was unseasonably colder, with strong winds dropping the temperature, making the July weekend feel like a winter trip along the Pacific Ocean. The racing was not affected, however, as a number of drivers added to their win totals to help their title chase hopes.