Iowa Citizen Population By County in 2021 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2021, the citizen population for Iowa was 3,079,625 and represented 96.87% of the total Iowa population.

Among all Iowa counties, Polk had the highest citizen population (463.87K), followed by Linn (222.26K), and Scott (170.88K).

In terms of percentages, Adams had the highest percentage of its population being citizens (100.00%), followed by Monona (99.94%), and Monroe (99.93%).

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:
Iowa Citizen Voting-age Population By County in 2021

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

See this for other years:

Iowa Citizen Population By County in 2021

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County	Citizen Population	% of County Population
Polk	463870	94.89
Linn	222260	97.24
Scott	170880	98.11
Johnson	140660	92.64
Black Hawk	126285	96.11
Woodbury	99810	94.97
Dubuque	97080	98.37
Dallas	92255	95.50
Story	91840	93.61
Pottawattamie	91605	97.90
Warren	51610	99.52
Clinton	46225	99.22
Cerro Gordo	42815	99.14
Muscatine	41565	96.34
Des Moines	38570	98.72
Jasper	37095	98.43
Marshall	36860	91.84
Webster	36355	97.95
Sioux	34375	96.44
Wapello	33940	96.03
Lee	33530	99.42
Marion	33105	99.18
Boone	26545	99.35
Benton	25585	99.73
Plymouth	24885	97.42
Bremer	24655	99.16
Washington	22095	98.09
Mahaska	21935	99.12
Jones	20630	99.76
Carroll	20545	98.99
Buchanan	20400	99.03
Henry	20145	98.32
Winneshiek	19820	98.61
Jackson	19395	99.46
Fayette	19335	98.75
Cedar	18335	99.14
Poweshiek	18280	98.12
Buena Vista	18110	87.38
Delaware	17485	99.86
Dickinson	17245	98.35
Clayton	17040	99.21
Hardin	16695	98.24
Iowa	16520	99.55
Tama	16480	96.49
Madison	16375	99.76
Clay	16320	99.45
Floyd	15610	99.62
Page	15120	99.15
Hamilton	14795	98.14
Kossuth	14665	98.92
Crawford	14600	88.19
Harrison	14545	99.69
Mills	14545	99.22
Jefferson	14330	90.44
Butler	14290	99.10
O'Brien	13935	98.55
Allamakee	13700	97.37
Cass	12960	98.48
Wright	12635	97.34
Grundy	12255	99.35
Appanoose	12245	99.47
Union	12015	98.52
Chickasaw	11945	99.38
Lyon	11810	98.79
Cherokee	11590	99.87
Shelby	11590	98.64
Hancock	10735	99.08
Winnebago	10600	98.65
Guthrie	10450	98.59
Mitchell	10425	99.05
Montgomery	10315	99.90
Louisa	10160	93.30
Keokuk	9985	99.35
Calhoun	9915	99.55
Sac	9750	99.19
Franklin	9620	95.67
Humboldt	9435	98.08
Howard	9370	99.10
Clarke	9275	95.28
Emmet	9125	96.71
Davis	9030	99.61
Palo Alto	8890	98.83
Greene	8785	99.49
Monona	8725	99.94
Lucas	8490	98.15
Decatur	7590	98.32
Monroe	7585	99.93
Worth	7415	99.53
Adair	7380	99.19
Van Buren	7170	99.65
Pocahontas	6970	98.31
Ida	6920	99.14
Fremont	6680	99.70
Wayne	6475	99.54
Osceola	5970	96.76
Taylor	5740	96.80
Audubon	5620	99.38
Ringgold	4715	99.47
Adams	3695	100.00