Iowa Population By County in 2015

Updated on January 29, 2024.

Based on the US Census Vintage data estimates, in 2015, the population of Iowa was 3,122,541. Among all Iowa counties, Polk had the highest population (467,517), followed by Linn (220,392), and Scott (172,072). Adams was the least populated county (3,752).

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 2015
Iowa Population By County in 2015
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County Population % of State Population
Adair 7142 0.23
Adams 3752 0.12
Allamakee 13881 0.45
Appanoose 12587 0.40
Audubon 5707 0.18
Benton 25608 0.82
Black Hawk 133764 4.28
Boone 26468 0.85
Bremer 24755 0.79
Buchanan 21110 0.68
Buena Vista 20373 0.65
Butler 14880 0.48
Calhoun 9801 0.31
Carroll 20421 0.65
Cass 13354 0.43
Cedar 18257 0.59
Cerro Gordo 43006 1.38
Cherokee 11488 0.37
Chickasaw 12152 0.39
Clarke 9213 0.30
Clay 16498 0.53
Clayton 17726 0.57
Clinton 47593 1.52
Crawford 17069 0.55
Dallas 80658 2.58
Davis 8774 0.28
Decatur 8145 0.26
Delaware 17395 0.56
Des Moines 39909 1.28
Dickinson 17009 0.55
Dubuque 96934 3.10
Emmet 9708 0.31
Fayette 20143 0.65
Floyd 15920 0.51
Franklin 10318 0.33
Fremont 6910 0.22
Greene 8947 0.29
Grundy 12402 0.40
Guthrie 10653 0.34
Hamilton 15220 0.49
Hancock 11029 0.35
Hardin 17257 0.55
Harrison 14145 0.45
Henry 19862 0.64
Howard 9322 0.30
Humboldt 9562 0.31
Ida 6967 0.22
Iowa 16293 0.52
Jackson 19363 0.62
Jasper 36762 1.18
Jefferson 17913 0.57
Johnson 145114 4.65
Jones 20435 0.65
Keokuk 10169 0.33
Kossuth 15150 0.49
Lee 34916 1.12
Linn 220392 7.06
Louisa 11289 0.36
Lucas 8609 0.28
Lyon 11755 0.38
Madison 15727 0.50
Mahaska 22417 0.72
Marion 33123 1.06
Marshall 40340 1.29
Mills 14885 0.48
Mitchell 10670 0.34
Monona 8865 0.28
Monroe 7919 0.25
Montgomery 10153 0.33
Muscatine 43069 1.38
O'Brien 13927 0.45
Osceola 6161 0.20
Page 15466 0.50
Palo Alto 9137 0.29
Plymouth 24912 0.80
Pocahontas 6970 0.22
Polk 467517 14.97
Pottawattamie 93657 3.00
Poweshiek 18379 0.59
Ringgold 4978 0.16
Sac 9961 0.32
Scott 172072 5.51
Shelby 11799 0.38
Sioux 34764 1.11
Story 96744 3.10
Tama 17214 0.55
Taylor 6243 0.20
Union 12431 0.40
Van Buren 7297 0.23
Wapello 35450 1.14
Warren 48486 1.55
Washington 22160 0.71
Wayne 6359 0.20
Webster 37089 1.19
Winnebago 10612 0.34
Winneshiek 20756 0.67
Woodbury 102532 3.28
Worth 7503 0.24
Wright 12843 0.41