| 1899 | Chicago (West Division) and Chicago (Medill) play first known interscholastic girls game of indoor baseball, the predecessor of softball. |
| 1976 | IHSA sponsors first state tournament in girls softball at Mineral Springs Park in Pekin. Richton Park (Rich South) wins the championship. |
| 1985 | State Final split into Class A (small schools), won by Freeburg, and Class AA (large schools), won by Rock Island (Alleman). |
| 2002 | Added Super-Sectional level to state series. |
| 2008 | State Final split into four classes (1A-2A-3A-4A). |