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Population of Counties in Iowa (2024)

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2024 Population
Growth Since 2020
Area (mi²)
Density (/mi²)
Polk County509,3263.31%221890Polk County location
Linn County229,004-0.61%277319Linn County location
Scott County174,7890.1%177382Scott County location
Johnson County158,1413.32%237258Johnson County location
Black Hawk County130,890-0.12%218231Black Hawk County location
Dallas County114,03813.43%227194Dallas County location
Woodbury County106,3440.41%337122Woodbury County location
Dubuque County99,059-0.25%235163Dubuque County location
Story County98,8750.23%221173Story County location
Pottawattamie County93,293-0.4%36798Pottawattamie County location
Warren County56,1076.69%22098Warren County location
Clinton County46,061-0.79%26866Clinton County location
Cerro Gordo County42,386-1.48%21975Cerro Gordo County location
Muscatine County42,041-2.55%16996Muscatine County location
Marshall County40,2070.28%22170Marshall County location
Des Moines County38,264-1.44%16192Des Moines County location
Jasper County37,8890.21%28252Jasper County location
Sioux County36,3651.34%29647Sioux County location
Webster County36,318-1.83%27651Webster County location
Wapello County35,251-0.21%16782Wapello County location
Marion County33,9101.48%21461Marion County location
Lee County32,301-3.67%20062Lee County location
Boone County26,601-0.36%22047Boone County location
Benton County25,8501.18%27636Benton County location
Plymouth County25,7220.12%33330Plymouth County location
Bremer County25,3601.4%16858Bremer County location
Washington County22,5780.16%22040Washington County location
Mahaska County21,777-1.73%22038Mahaska County location
Jones County20,8510.96%22236Jones County location
Buchanan County20,6930.43%22036Buchanan County location
Carroll County20,503-1.08%22036Carroll County location
Buena Vista County20,490-1.52%22236Buena Vista County location
Winneshiek County19,728-1.58%26629Winneshiek County location
Jackson County19,338-0.6%24530Jackson County location
Fayette County19,154-1.5%28226Fayette County location
Henry County18,841-7.85%16843Henry County location
Poweshiek County18,388-1.3%22631Poweshiek County location
Cedar County18,251-1.32%22332Cedar County location
Dickinson County18,0641.67%14747Dickinson County location
Delaware County17,5930.77%22330Delaware County location
Madison County16,9021.64%21730Madison County location
Clayton County16,881-0.89%30022Clayton County location
Tama County16,723-2.1%27823Tama County location
Clay County16,5151.1%21929Clay County location
Hardin County16,312-3.07%22029Hardin County location
Iowa County16,265-2.36%22628Iowa County location
Crawford County15,897-3.56%27622Crawford County location
Floyd County15,304-1.92%19331Floyd County location
Jefferson County15,212-3.07%16835Jefferson County location
Page County14,852-2.23%20728Page County location
Mills County14,7312.31%16934Mills County location
Harrison County14,6600.62%26921Harrison County location
Hamilton County14,655-2.35%22325Hamilton County location
Kossuth County14,327-3.19%37615Kossuth County location
Allamakee County14,1300.42%24722Allamakee County location
Butler County14,098-1.64%22424Butler County location
O'Brien County13,939-1.49%22124O'Brien County location
Cass County13,1230%21823Cass County location
Wright County12,617-2.31%22422Wright County location
Lyon County12,4714.53%22721Lyon County location
Grundy County12,4130.65%19425Grundy County location
Appanoose County12,097-1.55%19224Appanoose County location
Union County11,909-1.84%16428Union County location
Shelby County11,9011.41%22820Shelby County location
Cherokee County11,7200.55%22320Cherokee County location
Chickasaw County11,588-3.34%19523Chickasaw County location
Guthrie County10,7631.42%22818Guthrie County location
Hancock County10,579-1.63%22019Hancock County location
Winnebago County10,503-1.49%15426Winnebago County location
Mitchell County10,492-0.99%18122Mitchell County location
Louisa County10,409-3.75%15526Louisa County location
Montgomery County10,068-2.56%16424Montgomery County location
Keokuk County9,945-0.59%22317Keokuk County location
Franklin County9,804-1.98%22517Franklin County location
Calhoun County9,801-1%22017Calhoun County location
Sac County9,683-1.18%22217Sac County location
Clarke County9,533-2.1%16622Clarke County location
Humboldt County9,479-1.25%16822Humboldt County location
Emmet County9,244-1.1%15323Emmet County location
Howard County9,243-2.59%18320Howard County location
Davis County9,1910.88%19418Davis County location
Palo Alto County8,830-1.74%21816Palo Alto County location
Lucas County8,7922.02%16620Lucas County location
Monona County8,480-3%26812Monona County location
Greene County8,458-3.36%22015Greene County location
Decatur County7,6350.38%20514Decatur County location
Monroe County7,478-1.51%16817Monroe County location
Adair County7,321-2.3%22013Adair County location
Worth County7,283-2.06%15418Worth County location
Van Buren County7,2800.8%18715Van Buren County location
Pocahontas County6,879-2.63%22312Pocahontas County location
Ida County6,761-3.72%16716Ida County location
Wayne County6,6241.72%20313Wayne County location
Fremont County6,441-1.9%19713Fremont County location
Taylor County5,9731.89%20511Taylor County location
Osceola County5,884-5.07%15415Osceola County location
Audubon County5,493-3.34%17112Audubon County location
Ringgold County4,596-0.93%2079Ringgold County location
Adams County3,487-5.99%1638Adams County location
showing: 99 rows

There are 99 counties in Iowa. In 2019, in the state of Iowa, the most populous county is Polk County, home to the city of Des Moines, which has a population of 478,204 people. Since the time of the last United States census in 2010, Polk County has seen a population growth rate of 12.68%. Following Polk County are Linn County with a population of 225,909 and a growth rate of 6.71%, Scott County with a population of 173,283 and a growth rate of 4.85%, and Johnson County with a population of 151,260 and a growth rate of 15.17%. The only other Iowa counties with more than 100,000 residents are Black Hawk County (132,408) and Woodbury County (102,539), both of which had modest growth of less than 1%. Johnson County had the highest growth rate of 15.17% since 2010.

Iowa Counties with the Fewest Residents

The Iowa county with the lowest population is Adams County, which has a population of just 3,648 as of 2019. This represents a decrease in the population of 9.4% since 2010. Behind Adams County are Ringgold County (4,968), Audubon County (5,506), and Osceola County (6,040). Iowa has 25 counties with fewer than 10,000 people. Of these counties, all have experienced a declining population except two -- Davis County (9,017) and Clarke County (9,423) -- with the greatest decline in Emmet County (-9.96).

Iowa Counties with Rapid Growth

The county in Iowa with the most rapid population growth is Dallas County. Since 2010, Dallas County has been the fastest-growing county in Iowa, growing an amazing 35.11% with the population now standing at 90,180 in 2019. Behind Dallas County in growth are Johnson County (15.17%), Polk County (12.68%), and Warren County (10.17%). Emmet County has seen the highest level of population loss with a growth rate of -9.96% since 2010.

Lists of Counties in all States

  1. Iowa Profile
  2. Iowa State Data Center
  3. US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
  4. US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
  5. American Community Survey (2009 - 2013)
  6. Census QuickFacts
  7. Historical Populations of States and Counties (1790 - 1990)