The 1991 Champion Spark Plug 400 was the 19th stock car race of the 1991 NASCAR Winston Cup Series season and the 23rd iteration of the event. The race was held on Sunday, August 18, 1991, before an audience of 90,000 in Brooklyn, Michigan, at Michigan International Speedway, a two-mile (3.2 km) moderate-banked D-shaped speedway. The race took the scheduled 200 laps to complete. In the final laps of the race, Wood Brothers Racing driver Dale Jarrett would mount a late-race charge against Robert Yates Racing driver Davey Allison, passing Allison in the final lap of the race and besting Allison by 8 inches (20 cm) at the finish to take his first career NASCAR Winston Cup Series victory and his only victory of the season. To fill out the top three, Penske Racing South driver Rusty Wallace would finish third.