The first California Jam festival takes place at the Ontario Motor Speedway in Ontario, California. Co-headlined by Deep Purple and Emerson, Lake & Pa...

The first California Jam festival takes place at the Ontario Motor Speedway in Ontario, California. Co-headlined by Deep Purple and Emerson, Lake & Palmer. The festival set what were then records for the loudest amplification system ever installed, the highest paid attendance, and highest gross in history.