Illinois Voting-age Population By County in 2021 (ACS-5Yrs)

Updated on February 28, 2025.

Based on the US Census ACS-5Yrs estimates, in 2021, the voting-age population of Illinois was 9.93M which was 77.48% of the total Illinois population. Among all Illinois counties, Cook had the highest voting-age population (4.11M), followed by DuPage (721.39K), and Lake (542.06K).

On the other hand, the counties with the least voting-age population were: Pope (3.13K), Hardin (3.19K), and Calhoun (3.62K).

The chart and table below shows the voting-age population of each county and the percentage of each county's population that are of voting-age.

You can see similar information for other states and by state for the United States.

Related Topics: Illinois ACS-5Yrs Estimates, 2021 Topic List.

Data Source: US Census - ACS 5-Year Estimates, 2021 Census.

Illinois Voting-age Population By County in 2021

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County	Voting-age Population	% of County Population
Adams	50882	77.24
Alexander	4242	77.30
Bond	13668	81.34
Boone	40386	75.36
Brown	5227	82.58
Bureau	26194	78.57
Calhoun	3620	79.79
Carroll	12541	80.46
Cass	9847	75.41
Champaign	167098	80.89
Christian	26817	78.79
Clark	11967	76.78
Clay	10249	76.99
Clinton	29113	78.58
Coles	38896	81.81
Cook	4113751	78.13
Crawford	15116	80.30
Cumberland	8124	77.17
DeKalb	79037	78.32
De Witt	12288	78.50
Douglas	14789	75.04
DuPage	721393	77.23
Edgar	13621	80.13
Edwards	4817	77.28
Effingham	26252	75.93
Fayette	16944	78.76
Ford	10458	76.96
Franklin	29554	77.64
Fulton	27286	80.20
Gallatin	4033	80.05
Greene	9552	78.38
Grundy	39141	74.75
Hamilton	6268	78.15
Hancock	14034	79.07
Hardin	3189	86.19
Henderson	5289	81.56
Henry	38361	77.64
Iroquois	21343	78.00
Jackson	43552	81.14
Jasper	7174	76.94
Jefferson	28975	77.55
Jersey	17143	79.61
Jo Daviess	17811	80.98
Johnson	10690	80.75
Kane	387240	74.66
Kankakee	83336	77.09
Kendall	93603	71.58
Knox	40151	79.99
Lake	542057	75.87
LaSalle	86278	78.44
Lawrence	12520	80.96
Lee	27522	80.07
Livingston	28037	78.09
Logan	22773	80.65
McDonough	22934	82.67
McHenry	237841	76.54
McLean	134442	78.41
Macon	80848	77.49
Macoupin	35578	78.80
Madison	207634	78.03
Marion	28889	76.46
Marshall	9346	79.33
Mason	10469	79.16
Massac	11133	77.96
Menard	9518	77.11
Mercer	12398	78.57
Monroe	26961	77.63
Montgomery	22695	79.68
Morgan	26822	80.82
Moultrie	10872	74.29
Ogle	40064	77.36
Peoria	138668	76.01
Perry	17051	80.59
Piatt	12926	77.57
Pike	11521	77.20
Pope	3127	81.86
Pulaski	4165	78.90
Putnam	4485	79.55
Randolph	24677	80.56
Richland	12134	76.43
Rock Island	112137	77.50
St. Clair	197437	76.35
Saline	18710	78.39
Sangamon	152835	77.68
Schuyler	5743	82.60
Scott	3846	78.12
Shelby	16570	78.31
Stark	4278	78.70
Stephenson	35136	78.40
Tazewell	101880	77.19
Union	13591	78.75
Vermilion	57187	76.30
Wabash	8863	77.65
Warren	13207	78.21
Washington	10901	78.84
Wayne	12547	77.21
White	10878	77.93
Whiteside	43534	77.83
Will	523977	75.24
Williamson	52498	78.04
Winnebago	218063	76.39
Woodford	29197	75.70