High Quality Content by WIKIPEDIA articles! Southern Illinois University is a public research university located in Carbondale, Illinois, United States. Founded in 1869, SIU is the flagship campus of the Southern Illinois University system. (The other members are Southern Illinois University Edwardsville, Southern Illinois University School of Medicine, and Southern Illinois University School of Dental Medicine.) The university is known in official parlance as SIUC but colloquially as SIU. SIU`s total undergraduate enrollment is around 20,000.