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:
1831–1836Cook
1833–1836Iroquois
1826–1836Vermilion
1825–1827Putnam
1823–1825Edgar
1823–1825Fulton
1819–1823Clark
1821–1823Pike
1816–1823Crawford
1815–1816Edwards
1812–1815Madison
1801–1812St. Clair
1790–1801Knox, Northwest Territory
County Seat:
1836–Joliet—Name changed from Juliet on May 24, 1845.
History of county governing board:
1836–1850County Commissioners’ Court
1850–County Board of Supervisors
Township Government
Adopted:November 6, 1849
Township Names:
Channahon
Crete
CusterFormed from Reed and Wilmington (date unknown).
DuPage
FlorenceFormed from Wilmington (date unknown).
Frankfort
Green GardenFormed from east half of Trenton (date unknown).
Homer
Jackson
Joliet
Lockport
ManhattanFormed from west half of Trenton (date unknown).
MoneeName changed from Carcy (date unknown).
New LenoxName changed from Vernon on June 10, 1850.
PeotoneFormed from east half of Wilton (date unknown).
Plainfield
ReedName changed from Clinton on June 10, 1850.
Troy
WashingtonFormed from Crete and Sherburn (date unknown).
WesleyFormed from southeast part of Wilmington (date unknown).
Wheatland
WillFormed 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.