Iowa Population By County in 2021 (ACS-5Yrs)
Updated on February 28, 2025.
Based on the US Census ACS-5Yrs estimates, in 2021, the total population of Iowa was 3.18M. Among all Iowa counties, Polk was the most populated county (488.87K), followed by Linn (228.57K), and then Scott (174.17K).
On the other hand, the least populated counties were: Adams (3.70K), Ringgold (4.74K), and Audubon (5.66K).
The chart and table below shows the population of each county and the percentage of Iowa population in each county.
You can see similar information for other states and by state for the United States.
Related Topics: Iowa ACS-5Yrs Estimates, 2021 Topic List.
Data Source: US Census - ACS 5-Year Estimates, 2021 Census.
Iowa Population By County in 2021
Iowa Population By County in 2021
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| County | Population | % of State Population |
|---|---|---|
| Adair | 7439 | 0.23 |
| Adams | 3697 | 0.12 |
| Allamakee | 14068 | 0.44 |
| Appanoose | 12310 | 0.39 |
| Audubon | 5657 | 0.18 |
| Benton | 25654 | 0.81 |
| Black Hawk | 131396 | 4.13 |
| Boone | 26721 | 0.84 |
| Bremer | 24863 | 0.78 |
| Buchanan | 20598 | 0.65 |
| Buena Vista | 20723 | 0.65 |
| Butler | 14421 | 0.45 |
| Calhoun | 9962 | 0.31 |
| Carroll | 20756 | 0.65 |
| Cass | 13158 | 0.41 |
| Cedar | 18494 | 0.58 |
| Cerro Gordo | 43185 | 1.36 |
| Cherokee | 11606 | 0.37 |
| Chickasaw | 12021 | 0.38 |
| Clarke | 9736 | 0.31 |
| Clay | 16410 | 0.52 |
| Clayton | 17173 | 0.54 |
| Clinton | 46589 | 1.47 |
| Crawford | 16555 | 0.52 |
| Dallas | 96604 | 3.04 |
| Davis | 9066 | 0.28 |
| Decatur | 7718 | 0.24 |
| Delaware | 17508 | 0.55 |
| Des Moines | 39069 | 1.23 |
| Dickinson | 17536 | 0.55 |
| Dubuque | 98687 | 3.10 |
| Emmet | 9433 | 0.30 |
| Fayette | 19582 | 0.62 |
| Floyd | 15672 | 0.49 |
| Franklin | 10056 | 0.32 |
| Fremont | 6702 | 0.21 |
| Greene | 8831 | 0.28 |
| Grundy | 12336 | 0.39 |
| Guthrie | 10599 | 0.33 |
| Hamilton | 15073 | 0.47 |
| Hancock | 10837 | 0.34 |
| Hardin | 16997 | 0.54 |
| Harrison | 14589 | 0.46 |
| Henry | 20488 | 0.64 |
| Howard | 9456 | 0.30 |
| Humboldt | 9622 | 0.30 |
| Ida | 6979 | 0.22 |
| Iowa | 16596 | 0.52 |
| Jackson | 19499 | 0.61 |
| Jasper | 37686 | 1.19 |
| Jefferson | 15846 | 0.50 |
| Johnson | 151833 | 4.78 |
| Jones | 20680 | 0.65 |
| Keokuk | 10050 | 0.32 |
| Kossuth | 14823 | 0.47 |
| Lee | 33724 | 1.06 |
| Linn | 228567 | 7.19 |
| Louisa | 10891 | 0.34 |
| Lucas | 8650 | 0.27 |
| Lyon | 11953 | 0.38 |
| Madison | 16414 | 0.52 |
| Mahaska | 22132 | 0.70 |
| Marion | 33381 | 1.05 |
| Marshall | 40137 | 1.26 |
| Mills | 14658 | 0.46 |
| Mitchell | 10526 | 0.33 |
| Monona | 8732 | 0.28 |
| Monroe | 7589 | 0.24 |
| Montgomery | 10327 | 0.33 |
| Muscatine | 43145 | 1.36 |
| O'Brien | 14139 | 0.45 |
| Osceola | 6168 | 0.19 |
| Page | 15250 | 0.48 |
| Palo Alto | 8996 | 0.28 |
| Plymouth | 25543 | 0.80 |
| Pocahontas | 7091 | 0.22 |
| Polk | 488871 | 15.38 |
| Pottawattamie | 93571 | 2.94 |
| Poweshiek | 18628 | 0.59 |
| Ringgold | 4739 | 0.15 |
| Sac | 9829 | 0.31 |
| Scott | 174170 | 5.48 |
| Shelby | 11750 | 0.37 |
| Sioux | 35647 | 1.12 |
| Story | 98106 | 3.09 |
| Tama | 17079 | 0.54 |
| Taylor | 5932 | 0.19 |
| Union | 12193 | 0.38 |
| Van Buren | 7196 | 0.23 |
| Wapello | 35343 | 1.11 |
| Warren | 51862 | 1.63 |
| Washington | 22525 | 0.71 |
| Wayne | 6504 | 0.21 |
| Webster | 37114 | 1.17 |
| Winnebago | 10743 | 0.34 |
| Winneshiek | 20100 | 0.63 |
| Woodbury | 105102 | 3.31 |
| Worth | 7450 | 0.23 |
| Wright | 12978 | 0.41 |