| 1898 | First annual swimming carnival features a single event, an 80-yard "schoolboy race," won by a swimmer from Chicago (English). |
| 1902 | Chicago (North Division), Chicago (Armour Academy), and Chicago (Lewis Institute) compete in the first known interscholastic swimming competition among Illinois high schools. |
| 1932 | IHSA sponsors first boys state swimming and diving meet at Maine Twp. High School in Des Plaines. |
| 1978 | Hinsdale (Central) wins record 12th consecutive state title. |