Iowa Population By County in 2018

Updated on December 2, 2021.

According to the US Census Bureau population estimates, there were 3,149,900 people living in Iowa in 2018. Polk County was the most populated county with 486,222 residents, followed by Linn County with 226,060 residents, and Scott County with 173,019 residents. Adams County with a population of 3,628 was the least populated county in Iowa in 2018.

Use the map below to interactively explore the population of each county in Iowa in 2018. The data can also be explored further by sorting and filtering with the table below.

Hover/Click on the counties to see the values.
Iowa Population By County (2018)
See also Population estimate for other years:
Table of Iowa Population By County in 2018
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County Population % of State Population
Adair 7,028 0.22%
Adams 3,628 0.12%
Allamakee 13,832 0.44%
Appanoose 12,467 0.40%
Audubon 5,482 0.17%
Benton 25,546 0.81%
Black Hawk 131,769 4.18%
Boone 26,356 0.84%
Bremer 25,022 0.79%
Buchanan 21,140 0.67%
Buena Vista 19,807 0.63%
Butler 14,516 0.46%
Calhoun 9,653 0.31%
Carroll 20,101 0.64%
Cass 12,959 0.41%
Cedar 18,508 0.59%
Cerro Gordo 42,643 1.35%
Cherokee 11,281 0.36%
Chickasaw 11,965 0.38%
Clarke 9,489 0.30%
Clay 16,167 0.51%
Clayton 17,515 0.56%
Clinton 46,506 1.48%
Crawford 17,081 0.54%
Dallas 89,999 2.86%
Davis 8,967 0.28%
Decatur 7,901 0.25%
Delaware 17,115 0.54%
Des Moines 39,259 1.25%
Dickinson 17,159 0.55%
Dubuque 96,961 3.08%
Emmet 9,276 0.29%
Fayette 19,643 0.62%
Floyd 15,784 0.50%
Franklin 10,081 0.32%
Fremont 6,956 0.22%
Greene 8,971 0.28%
Grundy 12,268 0.39%
Guthrie 10,719 0.34%
Hamilton 14,887 0.47%
Hancock 10,726 0.34%
Hardin 16,965 0.54%
Harrison 14,086 0.45%
Henry 20,015 0.64%
Howard 9,185 0.29%
Humboldt 9,520 0.30%
Ida 6,829 0.22%
Iowa 16,150 0.51%
Jackson 19,375 0.62%
Jasper 37,121 1.18%
Jefferson 18,102 0.57%
Johnson 151,003 4.79%
Jones 20,627 0.66%
Keokuk 10,221 0.32%
Kossuth 14,834 0.47%
Lee 33,929 1.08%
Linn 226,060 7.18%
Louisa 11,135 0.35%
Lucas 8,590 0.27%
Lyon 11,849 0.38%
Madison 16,140 0.51%
Mahaska 22,203 0.71%
Marion 33,251 1.06%
Marshall 39,879 1.27%
Mills 15,122 0.48%
Mitchell 10,536 0.33%
Monona 8,649 0.28%
Monroe 7,738 0.25%
Montgomery 9,976 0.32%
Muscatine 42,784 1.36%
O'Brien 13,806 0.44%
Osceola 6,020 0.19%
Page 15,227 0.48%
Palo Alto 8,910 0.28%
Plymouth 25,024 0.79%
Pocahontas 6,709 0.21%
Polk 486,222 15.44%
Pottawattamie 93,445 2.97%
Poweshiek 18,461 0.59%
Ringgold 4,921 0.16%
Sac 9,675 0.31%
Scott 173,019 5.49%
Shelby 11,564 0.37%
Sioux 34,767 1.10%
Story 96,749 3.07%
Tama 16,853 0.54%
Taylor 6,190 0.20%
Union 12,297 0.39%
Van Buren 7,008 0.22%
Wapello 35,060 1.11%
Warren 51,053 1.62%
Washington 22,095 0.70%
Wayne 6,376 0.20%
Webster 36,361 1.15%
Winnebago 10,555 0.34%
Winneshiek 20,026 0.64%
Woodbury 102,415 3.25%
Worth 7,416 0.24%
Wright 12,669 0.40%