Ranking of Iowa Counties By Population in 2021
Updated on June 18, 2025.
Based on the US Census Vintage data estimates, in 2021, the Population for Iowa was 3.20M. Among all Iowa counties, Polk County had the highest population (497.90K), followed by Linn County (229.47K), and Scott County (174.25K).
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), 2021 Census.
See this for other years:
Ranking of Iowa Counties By Population in 2021
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| Rank | County | Population |
|---|---|---|
| 1 | Polk County | 497903 |
| 2 | Linn County | 229474 |
| 3 | Scott County | 174250 |
| 4 | Johnson County | 155047 |
| 5 | Black Hawk County | 130587 |
| 6 | Woodbury County | 105801 |
| 7 | Dallas County | 104194 |
| 8 | Story County | 99683 |
| 9 | Dubuque County | 98863 |
| 10 | Pottawattamie County | 93403 |
| 11 | Warren County | 53487 |
| 12 | Clinton County | 46491 |
| 13 | Cerro Gordo County | 42767 |
| 14 | Muscatine County | 42693 |
| 15 | Marshall County | 39915 |
| 16 | Des Moines County | 38545 |
| 17 | Jasper County | 37887 |
| 18 | Webster County | 37172 |
| 19 | Sioux County | 35979 |
| 20 | Wapello County | 35304 |
| 21 | Marion County | 33450 |
| 22 | Lee County | 33260 |
| 23 | Boone County | 26770 |
| 24 | Benton County | 25745 |
| 25 | Plymouth County | 25738 |
| 26 | Bremer County | 25119 |
| 27 | Washington County | 22526 |
| 28 | Mahaska County | 21982 |
| 29 | Jones County | 20832 |
| 30 | Buena Vista County | 20794 |
| 31 | Carroll County | 20754 |
| 32 | Buchanan County | 20707 |
| 33 | Henry County | 20387 |
| 34 | Winneshiek County | 19944 |
| 35 | Jackson County | 19402 |
| 36 | Fayette County | 19303 |
| 37 | Poweshiek County | 18623 |
| 38 | Cedar County | 18429 |
| 39 | Dickinson County | 17876 |
| 40 | Delaware County | 17552 |
| 41 | Clayton County | 17058 |
| 42 | Tama County | 16862 |
| 43 | Madison County | 16792 |
| 44 | Hardin County | 16705 |
| 45 | Iowa County | 16583 |
| 46 | Clay County | 16459 |
| 47 | Crawford County | 16242 |
| 48 | Jefferson County | 15786 |
| 49 | Floyd County | 15458 |
| 50 | Page County | 15232 |
| 51 | Hamilton County | 14866 |
| 52 | Harrison County | 14692 |
| 53 | Kossuth County | 14511 |
| 54 | Mills County | 14491 |
| 55 | Butler County | 14351 |
| 56 | O'Brien County | 14048 |
| 57 | Allamakee County | 13965 |
| 58 | Cass County | 13085 |
| 59 | Wright County | 12821 |
| 60 | Grundy County | 12376 |
| 61 | Appanoose County | 12269 |
| 62 | Union County | 12048 |
| 63 | Lyon County | 12035 |
| 64 | Chickasaw County | 11882 |
| 65 | Shelby County | 11776 |
| 66 | Cherokee County | 11539 |
| 67 | Louisa County | 10736 |
| 68 | Hancock County | 10687 |
| 69 | Winnebago County | 10657 |
| 70 | Guthrie County | 10598 |
| 71 | Mitchell County | 10555 |
| 72 | Montgomery County | 10317 |
| 73 | Franklin County | 9949 |
| 74 | Keokuk County | 9912 |
| 75 | Calhoun County | 9894 |
| 76 | Sac County | 9771 |
| 77 | Clarke County | 9751 |
| 78 | Humboldt County | 9630 |
| 79 | Howard County | 9509 |
| 80 | Emmet County | 9333 |
| 81 | Davis County | 9155 |
| 82 | Palo Alto County | 8932 |
| 83 | Greene County | 8726 |
| 84 | Lucas County | 8708 |
| 85 | Monona County | 8595 |
| 86 | Decatur County | 7797 |
| 87 | Monroe County | 7586 |
| 88 | Adair County | 7522 |
| 89 | Worth County | 7374 |
| 90 | Van Buren County | 7256 |
| 91 | Pocahontas County | 7043 |
| 92 | Ida County | 6980 |
| 93 | Fremont County | 6584 |
| 94 | Wayne County | 6522 |
| 95 | Osceola County | 6174 |
| 96 | Taylor County | 5868 |
| 97 | Audubon County | 5645 |
| 98 | Ringgold County | 4636 |
| 99 | Adams County | 3641 |