PlainCities

Counties · Iowa

Counties of Iowa

Iowa has 99 counties. Polk County is the largest with 516,546 residents in 2025. 33 of the 99 gained residents between 2020 and 2025 by the Census Bureau's estimates.

What counties are in Iowa?

Sorted by the 2025 population estimate; sort by any column.

Counties of Iowa: 2025 estimate, change since 2020, ACS 2020-2024 5-year estimates
Polk County516,546+4.9%21112$83,576$262,100
Linn County232,028+0.8%1854$77,649$214,300
Scott County175,259+0.3%2148$78,277$222,000
Johnson County160,044+4.7%1336$74,935$308,600
Black Hawk County131,532+0.3%1239$66,417$188,900
Dallas County118,457+18.8%1819$102,379$355,600
Woodbury County106,649+0.6%1629$73,658$183,200
Story County101,291+2.8%1527$69,685$258,700
Dubuque County99,381+0.1%2127$77,630$237,300
Pottawattamie County92,996−0.7%1830$73,602$195,700
Warren County57,331+9.4%1614$94,588$269,600
Clinton County46,002−1.0%1612$66,981$160,600
Cerro Gordo County42,372−1.7%1312$68,189$166,400
Muscatine County41,853−3.2%1510$69,396$182,100
Marshall County39,890−0.5%1411$73,315$145,500
Jasper County38,153+0.9%1410$71,311$186,300
Des Moines County38,077−2.2%1111$62,928$136,500
Webster County36,838−0.4%1613$68,975$153,800
Sioux County36,774+2.5%149$86,098$250,100
Wapello County35,210−0.7%711$64,766$125,100
Marion County34,192+2.3%910$78,680$233,000
Lee County32,306−3.7%1311$62,382$141,400
Boone County26,799+0.3%127$83,531$212,400
Benton County26,004+1.6%157$86,962$208,200
Plymouth County25,697−0.0%126$83,251$228,900
Bremer County25,296+1.2%88$86,784$219,600
Washington County22,667+0.5%106$75,647$203,900
Mahaska County21,880−1.4%117$70,940$157,800
Jones County21,253+2.9%117$73,531$184,800
Buchanan County20,883+1.6%116$78,236$176,000
Buena Vista County20,449−1.8%106$71,719$159,500
Carroll County20,303−2.2%136$72,930$176,000
Winneshiek County19,733−1.7%95$79,066$259,200
Henry County19,349−5.5%145$67,436$164,300
Jackson County19,288−1.0%136$74,186$175,000
Fayette County19,047−2.4%167$60,165$136,800
Poweshiek County18,368−1.6%115$67,391$209,300
Cedar County18,359−0.7%115$80,602$211,300
Dickinson County18,077+2.1%106$75,432$270,700
Delaware County17,674+1.1%124$74,989$177,900
Madison County17,270+4.4%94$90,855$245,100
Clayton County16,845−1.1%186$67,242$168,500
Tama County16,796−1.8%136$70,781$148,600
Iowa County16,504−1.0%154$71,223$193,900
Hardin County16,455−2.5%136$65,069$122,500
Crawford County16,237−1.7%146$67,027$153,700
Clay County16,202−1.1%105$65,428$178,600
Jefferson County15,291−2.4%85$61,620$163,400
Hamilton County14,944−0.6%95$72,432$156,400
Floyd County14,901−4.7%105$68,557$143,500
Page County14,856−2.4%106$57,953$125,300
Mills County14,793+2.0%95$90,753$237,800
Harrison County14,623+0.3%125$79,535$176,000
Kossuth County14,322−3.4%176$67,697$148,300
Allamakee County14,238+1.3%65$70,694$172,300
O'Brien County14,220+0.2%84$68,356$173,100
Butler County14,049−2.0%105$73,715$165,400
Cass County12,960−1.3%85$63,013$150,300
Wright County12,801−1.1%85$67,190$119,600
Grundy County12,361+0.2%94$87,205$198,800
Lyon County12,354+3.5%83$76,746$230,000
Appanoose County12,077−1.9%115$54,934$124,200
Union County11,829−2.6%84$57,772$122,000
Shelby County11,689−0.5%134$72,738$164,000
Chickasaw County11,663−3.0%94$75,675$182,600
Cherokee County11,369−2.4%85$71,269$158,700
Guthrie County10,782+1.5%133$77,711$180,100
Mitchell County10,650+0.8%143$71,365$175,100
Hancock County10,528−2.5%134$70,601$141,400
Louisa County10,416−3.9%93$77,354$150,100
Winnebago County10,251−4.0%73$67,642$135,000
Montgomery County10,002−3.2%64$63,666$121,400
Franklin County9,868−1.4%123$59,894$124,100
Keokuk County9,797−2.3%174$62,329$118,700
Clarke County9,574−1.8%33$71,641$161,100
Calhoun County9,562−3.7%134$64,964$118,800
Sac County9,525−2.9%94$73,838$141,400
Howard County9,415−0.6%63$67,446$147,800
Humboldt County9,409−2.0%124$71,946$155,800
Davis County9,230+1.3%42$77,194$161,900
Emmet County9,107−3.0%64$63,730$114,100
Palo Alto County8,899−1.1%94$72,781$123,200
Lucas County8,847+2.5%54$61,793$120,200
Greene County8,658−1.2%84$63,409$155,400
Monona County8,539−2.5%104$68,377$142,900
Decatur County7,655−1.4%103$59,044$113,900
Monroe County7,406−2.3%53$70,996$156,300
Adair County7,403−1.3%73$68,092$160,400
Worth County7,338−1.5%83$78,008$145,800
Van Buren County7,131−1.0%102$61,161$114,600
Pocahontas County6,819−3.7%93$61,875$98,100
Ida County6,777−3.2%53$63,073$108,900
Wayne County6,738+3.7%83$61,964$111,300
Fremont County6,522−1.3%123$71,621$154,400
Osceola County5,980−3.5%52$69,239$122,600
Taylor County5,835−1.0%93$67,740$117,200
Audubon County5,509−2.9%53$58,229$121,900
Ringgold County4,642−0.4%132$73,346$156,200
Adams County3,617−2.5%52$71,875$131,600

Source: PEP Vintage 2025 (CO-EST2025); American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) · Census population estimates

How these figures are made: methodology and release checks · reading a margin of error · every state · corrections