Iowa 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 Iowa was 3,001,675 and represented 97.03% of the total Iowa population.

Among all Iowa counties, Polk had the highest citizen population (429.03K), followed by Linn (212.60K), and Scott (166.80K).

In terms of percentages, Howard had the highest percentage of its population being citizens (99.95%), followed by Davis (99.94%), and Audubon (99.92%).

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 2015

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

See this for other years:

Iowa Citizen Population By County in 2015

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County	Citizen Population	% of County Population
Polk	429030	94.84
Linn	212595	98.13
Scott	166795	98.12
Johnson	129745	93.05
Black Hawk	129210	97.52
Woodbury	96480	94.10
Dubuque	94650	98.69
Pottawattamie	91320	97.97
Story	87185	93.16
Dallas	71635	95.65
Clinton	47750	98.73
Warren	47325	99.55
Cerro Gordo	43060	99.03
Muscatine	41275	96.18
Des Moines	39850	99.11
Marshall	36920	90.14
Webster	36620	98.19
Jasper	36565	99.56
Lee	35060	99.12
Wapello	33200	94.01
Marion	32975	99.17
Sioux	32915	95.38
Boone	26305	99.64
Benton	25730	99.71
Plymouth	24510	98.61
Bremer	24295	99.00
Mahaska	22135	98.84
Washington	21735	98.73
Buchanan	20895	99.50
Winneshiek	20570	98.49
Carroll	20545	99.59
Fayette	20430	99.22
Jones	20430	99.37
Henry	19810	98.66
Jackson	19505	99.67
Poweshiek	18350	98.10
Cedar	18325	99.73
Buena Vista	18270	89.10
Clayton	17640	99.07
Delaware	17380	99.29
Tama	17130	98.00
Hardin	17075	98.16
Dickinson	16875	99.47
Clay	16360	98.94
Iowa	16235	99.33
Floyd	15930	99.25
Crawford	15585	90.35
Madison	15480	98.95
Page	15445	98.63
Jefferson	15330	88.51
Kossuth	15170	99.28
Hamilton	14940	97.68
Butler	14900	99.57
Mills	14830	99.80
Harrison	14405	99.59
O'Brien	13855	98.33
Allamakee	13570	96.52
Cass	13555	99.74
Appanoose	12600	99.45
Union	12475	99.21
Wright	12425	96.06
Grundy	12390	99.88
Chickasaw	12115	98.94
Shelby	11840	98.75
Cherokee	11790	99.45
Lyon	11625	99.15
Hancock	10975	98.96
Mitchell	10735	99.77
Guthrie	10650	99.16
Louisa	10520	93.35
Winnebago	10470	98.63
Montgomery	10315	98.57
Keokuk	10240	99.51
Franklin	10230	97.52
Sac	10060	99.60
Calhoun	9900	99.85
Emmet	9610	96.92
Humboldt	9495	98.14
Howard	9490	99.95
Greene	9125	99.46
Monona	9010	99.12
Palo Alto	9010	97.83
Clarke	8925	96.18
Davis	8735	99.94
Lucas	8505	97.42
Decatur	8130	98.55
Monroe	7895	98.69
Worth	7550	99.80
Van Buren	7420	99.87
Adair	7380	99.39
Fremont	7080	99.65
Ida	7040	99.58
Pocahontas	7005	98.32
Wayne	6380	99.92
Taylor	6045	97.27
Osceola	6010	96.78
Audubon	5865	99.92
Ringgold	5050	99.80
Adams	3880	99.74