Iowa Citizen Population By County in 2020 (ACS-5Yrs)

Updated on March 28, 2026.

Based on the US Census Bureau's special tabulation from the ACS 5-year estimates, in 2020, the citizen population for Iowa was 3,049,520 and represented 96.81% of the total Iowa population.

Among all Iowa counties, Polk had the highest citizen population (460.90K), followed by Linn (219.86K), and Scott (169.29K).

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

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 2020

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

See this for other years:

Iowa Citizen Population By County in 2020

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County	Citizen Population	% of County Population
Polk	460900	94.95
Linn	219855	97.45
Scott	169290	97.89
Johnson	138785	92.02
Black Hawk	126275	95.80
Woodbury	98180	95.61
Dubuque	95705	98.47
Pottawattamie	91460	97.84
Story	90290	92.74
Dallas	86375	95.53
Warren	50630	99.54
Clinton	46290	99.05
Cerro Gordo	42275	99.07
Muscatine	41185	96.44
Des Moines	38705	98.67
Jasper	36445	98.42
Marshall	36370	91.37
Webster	35650	98.07
Lee	33765	99.47
Sioux	33580	96.22
Wapello	33510	95.47
Marion	32930	99.20
Boone	26190	99.28
Benton	25470	99.65
Bremer	24800	99.08
Plymouth	24510	97.49
Mahaska	22160	99.15
Washington	21535	97.44
Buchanan	21055	99.60
Jones	20465	99.47
Carroll	19935	98.93
Winneshiek	19820	98.66
Henry	19540	98.24
Fayette	19415	99.03
Jackson	19265	99.56
Cedar	18365	99.41
Poweshiek	18020	97.99
Clayton	17305	98.75
Buena Vista	17110	85.76
Delaware	17065	99.77
Dickinson	17035	98.70
Hardin	16690	98.61
Tama	16500	97.29
Jefferson	16275	89.65
Madison	16135	99.91
Iowa	16080	99.54
Clay	15985	99.04
Floyd	15635	99.49
Page	15030	98.85
Crawford	14940	87.88
Mills	14910	99.24
Kossuth	14675	98.72
Hamilton	14600	97.95
Butler	14430	99.45
Harrison	14010	99.75
O'Brien	13585	98.48
Allamakee	13440	97.67
Cass	12840	98.85
Appanoose	12425	99.72
Wright	12300	97.27
Grundy	12205	99.55
Union	12200	99.15
Chickasaw	11810	98.66
Lyon	11625	98.52
Shelby	11395	98.70
Cherokee	11245	99.69
Hancock	10580	98.79
Guthrie	10575	98.83
Mitchell	10535	99.48
Louisa	10400	93.48
Winnebago	10385	99.14
Keokuk	10085	99.21
Montgomery	10015	100.00
Franklin	9725	96.38
Sac	9620	99.07
Calhoun	9590	99.33
Humboldt	9360	98.32
Howard	9105	98.97
Emmet	9020	96.78
Davis	8960	99.83
Clarke	8930	95.15
Palo Alto	8845	98.94
Greene	8835	98.99
Monona	8675	100.00
Lucas	8380	97.95
Decatur	7775	98.29
Monroe	7755	99.94
Worth	7405	99.80
Van Buren	7075	99.58
Adair	6975	98.94
Fremont	6835	99.13
Ida	6790	98.98
Pocahontas	6595	98.07
Wayne	6395	99.53
Taylor	5995	97.32
Osceola	5825	96.84
Audubon	5515	99.73
Ringgold	4875	99.09
Adams	3625	99.73