The event was race number 9 of 12 in the 1980 CART PPG Indy Car World Series.

The race was the final California 500 before Ontario Motor Speedway closed at the end of the year.

On August 7, it was reported that the track would be sold to the Ontario Foothills Development Co, headed by Ted Dutton, for $42.15 million.

"[3] Ontario Motor Speedway General Manager Ray Smartis spoke highly of how the track had turned around since he took over in 1975.

[5] Unlike in 1979 when time trials were Formula One-style group qualifying, the field was set by a single car, two-lap average speed.

Bobby Unser continued his fast pace by winning the pole with an average speed of 195.200 mph.

Pancho Carter spun in oil and hit the wall in morning practice and did not set a qualifying speed.

To fill the final position, CART officials added Roger Rager to the field, highest in points among cars not qualified.

Track officials exercised their "promoter's option" and added Dick Ferguson, John Mahler, Jeff Heywood, and Chip Mead to the field to make a 37 car starting grid.

[7] Howdy Holmes suffered a violent crash in morning practice when his car veered into the turn three wall.

Holmes suffered a few cracked ribs and a headache but returned to the track later that afternoon after being treated at a local hospital.

On lap 24, John Mahler impacted the wall with the left side of his car in turn one.

Early in the race, Rick Mears took over the second position from Rutherford and was catching Unser until he cut a tire and made an unscheduled pit stop.

[21] The late-summer CART date in Southern California was transferred to Riverside International Raceway.