Iowa Citizen Population By County in 2018 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2018, the citizen population for Iowa was 3,032,105 and represented 96.80% of the total Iowa population.

Among all Iowa counties, Polk had the highest citizen population (449.62K), followed by Linn (216.66K), and Scott (168.30K).

In terms of percentages, Van Buren had the highest percentage of its population being citizens (99.93%), followed by Howard (99.89%), and Monroe (99.87%).

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 2018

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

See this for other years:

Iowa Citizen Population By County in 2018

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County	Citizen Population	% of County Population
Polk	449615	94.80
Linn	216655	97.54
Scott	168300	97.68
Johnson	135225	91.99
Black Hawk	128620	96.70
Woodbury	97815	95.52
Dubuque	95310	98.46
Pottawattamie	91215	97.55
Story	89550	92.40
Dallas	79960	95.19
Warren	49100	99.47
Clinton	46725	98.95
Cerro Gordo	42430	98.71
Muscatine	41525	96.68
Des Moines	39140	98.84
Jasper	36715	99.53
Marshall	36485	90.60
Webster	36090	98.19
Lee	34340	99.42
Wapello	33445	94.71
Sioux	33350	95.77
Marion	33080	99.62
Boone	26250	99.43
Benton	25530	99.63
Plymouth	24635	98.38
Bremer	24440	98.63
Mahaska	21925	98.72
Washington	21790	98.40
Buchanan	21055	99.67
Jones	20365	99.00
Carroll	20255	99.56
Winneshiek	20055	98.31
Fayette	19780	99.25
Henry	19630	98.52
Jackson	19325	99.64
Cedar	18400	99.76
Poweshiek	18195	97.80
Buena Vista	17665	87.19
Clayton	17465	98.84
Delaware	17205	99.68
Dickinson	16875	98.95
Hardin	16870	98.51
Tama	16650	97.17
Jefferson	16375	90.60
Iowa	16145	99.63
Clay	16075	98.53
Madison	15770	99.25
Floyd	15690	98.93
Page	15145	98.57
Kossuth	14960	99.24
Mills	14875	99.47
Hamilton	14845	98.25
Crawford	14825	86.54
Butler	14655	99.46
Harrison	14105	99.72
O'Brien	13665	98.24
Allamakee	13420	96.69
Cass	13025	98.75
Appanoose	12435	99.40
Wright	12395	96.80
Grundy	12315	99.80
Union	12310	98.84
Chickasaw	11885	98.22
Lyon	11635	98.85
Shelby	11585	99.06
Cherokee	11405	99.43
Hancock	10790	99.08
Mitchell	10605	99.77
Guthrie	10585	99.16
Winnebago	10450	98.87
Louisa	10365	92.34
Keokuk	10130	99.31
Franklin	10035	97.95
Montgomery	10010	98.57
Sac	9780	99.09
Calhoun	9740	99.59
Humboldt	9370	97.96
Emmet	9265	97.02
Howard	9255	99.89
Greene	8900	98.83
Davis	8860	99.72
Palo Alto	8785	97.02
Clarke	8760	94.40
Monona	8755	99.55
Lucas	8450	98.31
Decatur	7930	98.57
Monroe	7855	99.87
Worth	7470	99.73
Van Buren	7220	99.93
Adair	7045	98.88
Fremont	6905	99.07
Ida	6865	99.28
Pocahontas	6775	98.19
Wayne	6400	99.77
Taylor	6025	97.18
Osceola	5890	96.32
Audubon	5615	99.65
Ringgold	4935	99.00
Adams	3710	99.60