Each February, the Daytona Gatorade Duel is held as a preliminary event to the Daytona 500, and consists of two 150-mile races, while serving as a qualifying race for the Daytona 500. The finishing order in the two 150-mile Gatorade Duel races, held on the Thursday prior to the big race, determine the starting lineup for the Daytona 500 held that Sunday, thus making this a prominent event on both the NASCAR and Daytona calendars.
Qualifying for the Daytona 500, through this use of the Gatorade Duel, is unique in NASCAR with only the front row – pole and outside pole – starters being established through the conventional qualifying means of timed laps. After the two top positions are determined, the rest of the starting grid is determined by the finishing order of the two Gatorade Duel races. The entire Daytona 500 field is split into two groups, each racing in one of the qualifying races, and the finishing order of the first race fills the odd grid positions, while the order of the second qualifier fills the even ones.
The Duel event originally debuted as twin 100-mile races, and from 1959-1971 were counted with points going towards the Grand National championship, and prize money counted separately from the Daytona 500. Beginning in 1968, the races were scheduled to be lengthened to 125 miles, but cancelled due to rain, and leaving the starting lineup for that year's Daytona 500 to fall back on timed laps. In 1969, the races were actually run for 125 miles, or 50 laps; now requiring fuel stop, teams were challenged to change prior pit stop strategies.
With the commencement of NASCAR's modern era in 1971, the Daytona Gatorade Duel races were dropped as point-earning events for the Grand National Championship; as part of Winston Cup's changes to the series, races were now required to be at least 250 miles in order to qualify for official Championship points. The Duel races continued, serving only as the Daytona 500 qualifier and for whatever prize money was awarded, but no longer for official championship points.
