Willow Springs Raceway will celebrate its fiftieth anniversary next year. The track opened in 1953 on the former site of a Native American camping site and spring.
Motorcycle racing commenced in 1954 at Willow, according to former racer and Motorcyclist Editor Tony Murphy, who for many, many years had the motorcycle lap record at Willow. (His lap record in 1964: 1:41.)
Kenny Eggers is believed to have won the first AMA race at Willow in 1954--which would make that the first ever motorcycle win there.
Some say that Mike Hailwood won the first motorcycle race at Willow, but according to Murphy, his recollection is of Hailwood winning an AFM/FIM (The AFM was for many years the FIM rep in the US) race at Willow in 1961. Hailwood and other FIM riders of the time (John Cooper, etc) did race at Willow in the 1960s.