IRAD Fact Sheet for Will County Compiled by Ted Cash. The below information was obtained from the Illinois State Archives
| Established: | January 12, 1836 (Laws, 1836, p. 262) | ||
| Present area, or parts of it, formerly included in: | |||
| 18311836 | Cook | ||
| 18331836 | Iroquois | ||
| 18261836 | Vermilion | ||
| 18251827 | Putnam | ||
| 18231825 | Edgar | ||
| 18231825 | Fulton | ||
| 18191823 | Clark | ||
| 18211823 | Pike | ||
| 18161823 | Crawford | ||
| 18151816 | Edwards | ||
| 18121815 | Madison | ||
| 18011812 | St. Clair | ||
| 17901801 | Knox, Northwest Territory | ||
| County Seat: | |||
| 1836 | JolietName changed from Juliet on May 24, 1845. | ||
| History of county governing board: | |||
| 18361850 | County Commissioners Court | ||
| 1850 | County Board of Supervisors | ||
| Township Government | |||
| Adopted: | November 6, 1849 | ||
| Township Names: | |||
| Channahon | |||
| Crete | |||
| Custer | Formed from Reed and Wilmington (date unknown). | ||
| DuPage | |||
| Florence | Formed from Wilmington (date unknown). | ||
| Frankfort | |||
| Green Garden | Formed from east half of Trenton (date unknown). | ||
| Homer | |||
| Jackson | |||
| Joliet | |||
| Lockport | |||
| Manhattan | Formed from west half of Trenton (date unknown). | ||
| Monee | Name changed from Carcy (date unknown). | ||
| New Lenox | Name changed from Vernon on June 10, 1850. | ||
| Peotone | Formed from east half of Wilton (date unknown). | ||
| Plainfield | |||
| Reed | Name changed from Clinton on June 10, 1850. | ||
| Troy | |||
| Washington | Formed from Crete and Sherburn (date unknown). | ||
| Wesley | Formed from southeast part of Wilmington (date unknown). | ||
| Wheatland | |||
| Will | Formed from Carcy (now Monee) and Sherburn (date unknown). | ||
| Wilmington | |||
| Wilton | |||
| Notes: | |||
| Bourbonnais, Momence and Rockville were townships established in 1850, but the area therein became part of Kankakee County when it was formed in 1853. | |||
| Sherburn and Trenton were townships established in 1850, but the area therein was absorbed into other townships. See above. | |||