In the years when there were four days of time trials, if the second or third day of qualifying were to be rained out, neither would be made up (for example, this happened in 1980). If the final day of time trials ("Bump Day") was rained out, it would not be made up if the field had already filled to 33 cars (for example, this happened in 1984). If Bump Day were to be rained out, and the field was not filled to 33 cars yet, a special session would be held Monday (to date, this has occurred only once, in 1968).