Welcome to our alphabetical list of counties in Illinois A-Z! In addition to a comprehensive list of the 102 counties in Illinois, at the bottom of this page, we answer questions like: How many counties is in Illinois? What is Illinois smallest county? What is the largest county in Illinois by size? No matter the reason you’re doing research on Illinois’ geography, this alphabetical list of counties in Illinois A-Z has it all (and more).
A
Adams
Alexander
B
Bond
Boone
Brown
Bureau
C
Calhoun
Carroll
Cass
Champaign
Christian
Clark
Clay
Clinton
Coles
Cook
Crawford
Cumberland
D
DeKalb
DeWitt
Douglas
DuPage
E
Edgar
Edwards
Effingham
F
Fayette
Ford
Franklin
Fulton
G
Gallatin
Greene
Grundy
H
Hamilton
Hancock
Hardin
Henderson
Henry
I
Iroquois
J
Jackson
Jasper
Jefferson
Jersey
Jo Daviess
Johnson
K
Kane
Kankakee
Kendall
Knox
L
La Salle
Lake
Lawrence
Lee
Livingston
Logan
M
Macon
Macoupin
Madison
Marion
Marshall
Mason
Massac
McDonough
McHenry
McLean
Menard
Mercer
Monroe
Montgomery
Morgan
Moultrie
N
O
Ogle
P
Peoria
Perry
Piatt
Pike
Pope
Pulaski
Putnam
Q
R
Randolph
Richland
Rock Island
S
Saline
Sangamon
Schuyler
Scott
Shelby
St. Clair
Stark
Stephenson
T
Tazewell
U
Union
V
Vermilion
W
Wabash
Warren
Washington
Wayne
White
Whiteside
Will
Williamson
Winnebago
Woodford