The 2021 Southern Illinois 100 presented by Lucas Oil was the 17th stock car race of the 2021 ARCA Menards Series season, and the 35th iteration of the event.
In 1939 Hayes started buying adjoining stripmined land to develop its potential as parkland, replanting it and turning the strip pits into family-friendly ponds and lakes.
In the second race on October 10, popular AAA National driving champion Ted Horn was killed in the fourth turn when a spindle on his championship car broke.
The national championship race for the USAC Silver Crown dirt cars is held in his honor.
Jesse Love and Kelly Kovski did not make a qualifying lap, and had to start the race from the rear.