The 2023 Southern Illinois 100 was the 16th stock car race of the 2023 ARCA Menards Series season, and the 43rd iteration of the event. The race was held on Sunday, September 3, 2023, in Du Quoin, Illinois at the DuQuoin State Fairgrounds Racetrack, a 1-mile (1.6 km) permanent oval-shaped dirt track. The race took the scheduled 100 laps to complete. Jesse Love, driving for Venturini Motorsports, would put on a blistering performance, leading 80 of the 100 laps, and earning his 11th career ARCA Menards Series win, and his ninth of the season. Love would also extend his lead in the championship.^[4] To fill out the podium, Brent Crews, driving for Venturini Motorsports, and Will Kimmel, driving for family-owned Kimmel Racing, would finish 2nd and 3rd, respectively.

DuQuoin State Fairgrounds Racetrack is a one-mile (1.6-km) clay oval motor racetrack in Du Quoin, Illinois, about 90 miles (140 km) southeast of St Louis, Missouri. It is a stop on the ARCA Menards Series, USAC Silver Crown Series and American Flat Track.

The DuQuoin "Magic Mile" racetrack was constructed on reclaimed stripmine land in 1946 by W.R. Hayes. The track's first national championship race was held in September 1948. 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.

The first and only practice session was held on Sunday, September 3, at 4:30 PM CST, and would last for 30 minutes.^[5] Will Kimmel, driving for family-owned Kimmel Racing, would set the fastest time in the session, with a lap of 34.747, and an average speed of 103.606 mph (166.738 km/h).^[6]

Qualifying was held on Sunday, September 3, at 6:00 PM CST. The qualifying system used is a single-car, one-lap system with only one round. Whoever sets the fastest time in that round wins the pole.^[5] William Sawalich, driving for Joe Gibbs Racing, would score the pole for the race, with a lap of 34.595, and an average speed of 104.061 mph (167.470 km/h).^[7]