Population of Counties in (2018)

Name 2018 Population Growth Since 2010
Polk County481,83011.48%
Linn County224,1155.89%
Scott County172,5094.39%
Johnson County149,21013.65%
Black Hawk County132,6481.14%
Woodbury County102,4290.07%
Story County97,5028.79%
Dubuque County97,0413.31%
Pottawattamie County93,3860.04%
Dallas County87,23530.71%
Warren County50,1638.25%
Clinton County47,010-4.24%
Cerro Gordo County43,006-2.47%
Muscatine County42,8800.33%
Marshall County40,288-0.98%
Des Moines County39,417-2.04%
Jasper County36,9660.42%
Webster County36,605-3.37%
Wapello County35,044-1.74%
Sioux County34,8603.33%
Lee County34,295-4.33%
Marion County33,105-0.36%
Boone County26,4840.81%
Benton County25,642-1.56%
Plymouth County25,2201.00%
Bremer County24,9112.54%
Washington County22,2812.72%
Mahaska County22,235-0.76%
Buchanan County21,2021.07%
Jones County20,536-0.74%
Carroll County20,320-2.42%
Winneshiek County20,201-4.15%
Buena Vista County20,110-1.09%
Henry County19,863-1.19%
Fayette County19,796-5.09%
Jackson County19,366-2.31%
Cedar County18,5430.22%
Jefferson County18,4229.47%
Poweshiek County18,314-3.21%
Clayton County17,637-2.46%
Dickinson County17,1993.17%
Delaware County17,153-3.40%
Tama County17,058-3.73%
Crawford County17,056-0.59%
Hardin County17,048-2.82%
Clay County16,170-2.78%
Iowa County16,103-1.42%
Madison County16,0131.79%
Floyd County15,744-3.51%
Page County15,224-4.35%
Hamilton County15,115-3.30%
Mills County15,068-0.05%
Kossuth County14,999-3.38%
Butler County14,606-2.09%
Harrison County14,136-5.18%
Allamakee County13,884-3.40%
O'Brien County13,801-4.21%
Cass County13,145-5.63%
Wright County12,784-3.00%
Union County12,450-0.49%
Appanoose County12,352-3.92%
Grundy County12,333-1.06%
Chickasaw County12,005-3.24%
Lyon County11,7921.94%
Shelby County11,628-4.47%
Cherokee County11,316-6.60%
Louisa County11,184-1.72%
Hancock County10,771-4.68%
Guthrie County10,670-2.42%
Mitchell County10,631-1.46%
Winnebago County10,587-2.30%
Franklin County10,164-5.03%
Keokuk County10,153-3.39%
Montgomery County10,137-5.16%
Sac County9,817-5.19%
Calhoun County9,746-4.07%
Humboldt County9,564-2.33%
Emmet County9,432-8.14%
Clarke County9,3740.60%
Howard County9,228-3.57%
Palo Alto County9,092-3.26%
Greene County8,981-4.06%
Davis County8,9662.18%
Monona County8,740-5.49%
Lucas County8,534-4.06%
Decatur County7,950-5.57%
Monroe County7,845-1.88%
Worth County7,469-1.59%
Van Buren County7,157-5.57%
Adair County7,054-8.14%
Fremont County6,948-6.58%
Ida County6,865-2.86%
Pocahontas County6,846-6.08%
Wayne County6,4760.89%
Taylor County6,178-2.23%
Osceola County6,045-6.35%
Audubon County5,578-8.53%
Ringgold County5,034-1.56%
Adams County3,686-8.38%