Arie Luyendyk won the Indy 500, his first-ever victory in championship-level competition, and the fastest 500 until the 2013 Indianapolis 500.

In the second-to-last race of the season at Nazareth, Unser crashed out, giving Andretti a huge opportunity to close the gap.

Unser left Nazareth with a 27-point lead, enough to clinch the championship regardless of the results at the season finale at Laguna Seca.

For 1990, Bobby Rahal's team owned by Maurice Kranes merged with Rick Galles's and it became a two-car effort known as Galles-KRACO Racing.

Pat Patrick returned with a new team, taking over the Alfa Romeo Indy car effort.