Illinois Citizen Population By County in 2015 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2015, the citizen population for Illinois was 11,934,020 and represented 92.70% of the total Illinois population.

Among all Illinois counties, Cook had the highest citizen population (4.66M), followed by DuPage (853.61K), and Will (645.81K).

In terms of percentages, Gallatin had the highest percentage of its population being citizens (100.00%), followed by Hamilton (100.00%), and Hardin (100.00%).

The chart and table below shows the citizen population of each county and the percentage of each county's population that were citizens.

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

You may also be interested in:
Illinois Citizen Voting-age Population By County in 2015

Data Source: US Census - ACS 5-Year (CVAP).

See this for other years:

Illinois Citizen Population By County in 2015

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County	Citizen Population	% of County Population
Cook	4657865	88.95
DuPage	853605	91.75
Will	645810	94.42
Lake	635670	90.44
Kane	463200	88.25
McHenry	292520	95.17
Winnebago	277820	95.66
Madison	264150	98.80
St. Clair	263955	98.85
Sangamon	195840	98.41
Champaign	189940	92.31
Peoria	181380	96.94
McLean	165635	95.68
Rock Island	139725	94.95
Tazewell	134665	99.24
Kendall	115880	96.54
LaSalle	110370	98.04
Kankakee	108645	96.81
Macon	107780	98.70
DeKalb	99960	95.80
Vermilion	79320	98.69
Adams	66580	99.26
Williamson	66345	98.85
Jackson	56875	95.53
Whiteside	56785	98.71
Coles	52375	98.76
Knox	51320	98.48
Boone	50730	94.21
Ogle	50600	96.57
Grundy	49670	98.80
Henry	49310	98.85
Macoupin	46720	99.73
Stephenson	46230	99.15
Franklin	39475	99.45
Woodford	38905	99.49
Marion	38480	99.52
Jefferson	38230	99.09
Clinton	37690	99.37
Livingston	37385	99.19
Fulton	35740	98.39
Morgan	34745	98.90
Lee	34480	98.44
Christian	34105	99.72
Effingham	34075	99.26
Monroe	33440	99.70
Bureau	33295	97.60
Randolph	32860	99.37
McDonough	31215	97.52
Logan	29650	98.98
Montgomery	29175	99.40
Iroquois	28490	98.06
Saline	24645	99.44
Jersey	22480	99.36
Jo Daviess	22090	98.64
Fayette	22075	99.73
Shelby	22065	99.77
Perry	21695	99.47
Douglas	19395	97.83
Crawford	19365	99.10
Hancock	18630	99.41
Edgar	17920	99.61
Union	17300	98.58
Bond	17000	98.18
Warren	16830	95.09
Wayne	16480	99.55
Piatt	16420	99.55
Lawrence	16270	97.63
De Witt	16245	99.12
Pike	16075	99.57
Mercer	16065	99.75
Richland	16035	99.44
Clark	16015	99.10
Massac	14965	99.67
Moultrie	14830	99.36
Carroll	14680	98.36
Washington	14395	99.59
White	14375	99.38
Mason	14075	99.65
Ford	13760	99.46
Clay	13500	99.41
Greene	13475	99.82
Johnson	12735	99.26
Menard	12595	99.88
Cass	12175	91.85
Marshall	12065	99.10
Wabash	11450	98.28
Cumberland	10855	99.18
Jasper	9515	98.76
Hamilton	8320	100.00
Alexander	7320	99.39
Schuyler	7235	98.97
Henderson	7015	99.65
Brown	6710	97.81
Edwards	6645	99.93
Stark	5845	99.74
Pulaski	5835	99.40
Putnam	5745	98.71
Gallatin	5385	100.00
Scott	5180	99.62
Calhoun	4970	99.40
Pope	4325	99.89
Hardin	4230	100.00