According to jayski.com, the Busch Clash format has changed 14 times since 1979. Some of those changes were race rules, while some were eligibility changes. One consequence of race rule changes is that the length of the race also changed. So here’s the history of the length of the Busch Clash over the years.
The Busch Clash race length was 50 miles (20 laps) until 1998, when they added another five laps to make it 62.5 miles. The big change in length came in 2001, when the race jumped up to 70 laps. It settled out to 75 laps, with a few races going longer because of overtime.
The only time a Busch Clash hasn’t been run in its entirety was last year (2019) when only 59 out of the 75 laps were completed. The winner was Jimmie Johnson.