In Illinois high school football what is the mercy rule?

Illinois High School Association (IHSA) football does *not* have a formal "mercy rule" in the sense of a running clock or automatic game ending based on a point differential. They leave the matter to the discretion of the officiating crew and coaches. While there's no specific point margin, officials might encourage or allow a running clock in lopsided games to ensure sportsmanship and player safety. However, it is not mandated by any specific rule.