Ranking of Iowa Counties By Population in 2020
Updated on June 18, 2025.
Based on the US Census Vintage data estimates, in 2020, the Population for Iowa was 3.19M. Among all Iowa counties, Polk County had the highest population (493.04K), followed by Linn County (230.43K), and Scott County (174.62K).
The chart below shows the top 10 counties, and the table below shows the ranking of all Iowa counties.
You can see similar ranking information for related topics, and for other states. You can also see the ranking of all counties in the United States.
Related Topics: Iowa Census Vintage Data Topic List.
Data Source: US Census Bureau (Vintage), 2020 Census.
See this for other years:
Ranking of Iowa Counties By Population in 2020
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| Rank | County | Population |
|---|---|---|
| 1 | Polk County | 493039 |
| 2 | Linn County | 230433 |
| 3 | Scott County | 174617 |
| 4 | Johnson County | 153052 |
| 5 | Black Hawk County | 131049 |
| 6 | Woodbury County | 105952 |
| 7 | Dallas County | 100544 |
| 8 | Dubuque County | 99310 |
| 9 | Story County | 98651 |
| 10 | Pottawattamie County | 93655 |
| 11 | Warren County | 52591 |
| 12 | Clinton County | 46432 |
| 13 | Muscatine County | 43155 |
| 14 | Cerro Gordo County | 43021 |
| 15 | Marshall County | 40091 |
| 16 | Des Moines County | 38856 |
| 17 | Jasper County | 37818 |
| 18 | Webster County | 36991 |
| 19 | Sioux County | 35897 |
| 20 | Wapello County | 35327 |
| 21 | Lee County | 33529 |
| 22 | Marion County | 33414 |
| 23 | Boone County | 26702 |
| 24 | Plymouth County | 25694 |
| 25 | Benton County | 25550 |
| 26 | Bremer County | 25007 |
| 27 | Washington County | 22541 |
| 28 | Mahaska County | 22162 |
| 29 | Buena Vista County | 20808 |
| 30 | Carroll County | 20734 |
| 31 | Jones County | 20654 |
| 32 | Buchanan County | 20606 |
| 33 | Henry County | 20447 |
| 34 | Winneshiek County | 20051 |
| 35 | Jackson County | 19453 |
| 36 | Fayette County | 19448 |
| 37 | Poweshiek County | 18628 |
| 38 | Cedar County | 18483 |
| 39 | Dickinson County | 17773 |
| 40 | Delaware County | 17454 |
| 41 | Tama County | 17044 |
| 42 | Clayton County | 17034 |
| 43 | Hardin County | 16826 |
| 44 | Iowa County | 16653 |
| 45 | Madison County | 16628 |
| 46 | Crawford County | 16492 |
| 47 | Clay County | 16337 |
| 48 | Jefferson County | 15699 |
| 49 | Floyd County | 15593 |
| 50 | Page County | 15200 |
| 51 | Hamilton County | 15011 |
| 52 | Kossuth County | 14791 |
| 53 | Harrison County | 14567 |
| 54 | Mills County | 14418 |
| 55 | Butler County | 14334 |
| 56 | O'Brien County | 14149 |
| 57 | Allamakee County | 14069 |
| 58 | Cass County | 13115 |
| 59 | Wright County | 12923 |
| 60 | Grundy County | 12347 |
| 61 | Appanoose County | 12283 |
| 62 | Union County | 12128 |
| 63 | Chickasaw County | 11985 |
| 64 | Lyon County | 11923 |
| 65 | Shelby County | 11727 |
| 66 | Cherokee County | 11658 |
| 67 | Louisa County | 10825 |
| 68 | Hancock County | 10758 |
| 69 | Winnebago County | 10656 |
| 70 | Guthrie County | 10619 |
| 71 | Mitchell County | 10586 |
| 72 | Montgomery County | 10330 |
| 73 | Keokuk County | 10012 |
| 74 | Franklin County | 9995 |
| 75 | Calhoun County | 9895 |
| 76 | Sac County | 9800 |
| 77 | Clarke County | 9730 |
| 78 | Humboldt County | 9597 |
| 79 | Howard County | 9497 |
| 80 | Emmet County | 9342 |
| 81 | Davis County | 9115 |
| 82 | Palo Alto County | 8993 |
| 83 | Greene County | 8750 |
| 84 | Monona County | 8742 |
| 85 | Lucas County | 8620 |
| 86 | Decatur County | 7733 |
| 87 | Monroe County | 7596 |
| 88 | Adair County | 7489 |
| 89 | Worth County | 7430 |
| 90 | Van Buren County | 7218 |
| 91 | Pocahontas County | 7068 |
| 92 | Ida County | 7029 |
| 93 | Fremont County | 6567 |
| 94 | Wayne County | 6502 |
| 95 | Osceola County | 6200 |
| 96 | Taylor County | 5861 |
| 97 | Audubon County | 5680 |
| 98 | Ringgold County | 4643 |
| 99 | Adams County | 3710 |