Motocross in America was still in its infancy back in 1971. There was no AMA Pro Motocross Championship, let alone a supercross series. But the dirt bike boom was picking up steam. The Japanese manufacturers were all working on new bikes to challenge the dominant European brands, and the seminal film On Any Sunday was close to release. Dirt Bike, the first U.S. magazine “devoted completely to the off-road rider,” would launch in April. And Edison Dye’s Inter-Am tour, which brought professional motocross to America in 1967, had become such a success that the American Motorcyclist Association, established in 1924—the year the very first motocross race was held, in Great Britain—finally decided to start sanctioning motocross events.