Iowa Population By County in 2021

Updated on August 1, 2024.

Based on the US Census Vintage data estimates, in 2021, the population of Iowa was 3,197,944. Among all Iowa counties, Polk had the highest population (497,842), followed by Linn (229,445), and Scott (174,225). Adams was the least populated county (3,638).

Hover over or click on the counties in the map below to see the populations. The data can also be found in a table below. You can use the table to sort, filter, and explore the data further.

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

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Iowa Population By County in 2021
Iowa Population By County in 2021
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County Population % of State Population
Adair 7524 0.24
Adams 3638 0.11
Allamakee 13968 0.44
Appanoose 12269 0.38
Audubon 5645 0.18
Benton 25738 0.81
Black Hawk 130576 4.08
Boone 26761 0.84
Bremer 25118 0.79
Buchanan 20703 0.65
Buena Vista 20790 0.65
Butler 14348 0.45
Calhoun 9895 0.31
Carroll 20740 0.65
Cass 13089 0.41
Cedar 18436 0.58
Cerro Gordo 42761 1.34
Cherokee 11535 0.36
Chickasaw 11883 0.37
Clarke 9756 0.31
Clay 16454 0.52
Clayton 17053 0.53
Clinton 46483 1.45
Crawford 16232 0.51
Dallas 104174 3.26
Davis 9150 0.29
Decatur 7668 0.24
Delaware 17553 0.55
Des Moines 38506 1.20
Dickinson 17868 0.56
Dubuque 98854 3.09
Emmet 9334 0.29
Fayette 19295 0.60
Floyd 15465 0.48
Franklin 9952 0.31
Fremont 6583 0.21
Greene 8724 0.27
Grundy 12358 0.39
Guthrie 10588 0.33
Hamilton 14863 0.47
Hancock 10680 0.33
Hardin 16702 0.52
Harrison 14690 0.46
Henry 20382 0.64
Howard 9496 0.30
Humboldt 9630 0.30
Ida 6969 0.22
Iowa 16586 0.52
Jackson 19399 0.61
Jasper 37874 1.18
Jefferson 15781 0.49
Johnson 155035 4.85
Jones 20826 0.65
Keokuk 9902 0.31
Kossuth 14515 0.45
Lee 33257 1.04
Linn 229445 7.18
Louisa 10724 0.34
Lucas 8706 0.27
Lyon 12040 0.38
Madison 16793 0.53
Mahaska 21974 0.69
Marion 33441 1.05
Marshall 39913 1.25
Mills 14467 0.45
Mitchell 10563 0.33
Monona 8598 0.27
Monroe 7581 0.24
Montgomery 10316 0.32
Muscatine 42674 1.33
O'Brien 14044 0.44
Osceola 6170 0.19
Page 15220 0.48
Palo Alto 8923 0.28
Plymouth 25731 0.81
Pocahontas 7039 0.22
Polk 497842 15.57
Pottawattamie 93410 2.92
Poweshiek 18624 0.58
Ringgold 4632 0.14
Sac 9768 0.31
Scott 174225 5.45
Shelby 11780 0.37
Sioux 35959 1.12
Story 99679 3.12
Tama 16898 0.53
Taylor 5866 0.18
Union 12049 0.38
Van Buren 7258 0.23
Wapello 35295 1.10
Warren 53485 1.67
Washington 22522 0.70
Wayne 6531 0.20
Webster 37170 1.16
Winnebago 10661 0.33
Winneshiek 19935 0.62
Woodbury 105749 3.31
Worth 7377 0.23
Wright 12813 0.40