| County | Rank | Change (2020) ↓ | 2026 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Dallas County | 1 | 22.18% | 122,843 | 100,544 |
| Warren County | 2 | 11.11% | 58,433 | 52,591 |
| Polk County | 3 | 8.22% | 533,581 | 493,039 |
| Johnson County | 4 | 7.05% | 163,836 | 153,052 |
| Story County | 5 | 5.92% | 104,492 | 98,651 |
| Lyon County | 6 | 5.33% | 12,558 | 11,923 |
| Madison County | 7 | 5.15% | 17,485 | 16,628 |
| Wayne County | 8 | 4.31% | 6,782 | 6,502 |
| Jones County | 9 | 4.16% | 21,514 | 20,654 |
| Marion County | 10 | 3.87% | 34,708 | 33,414 |
| O'Brien County | 11 | 3.51% | 14,646 | 14,149 |
| Mills County | 12 | 3.11% | 14,867 | 14,418 |
| Dickinson County | 13 | 2.97% | 18,300 | 17,773 |
| Franklin County | 14 | 2.87% | 10,282 | 9,995 |
| Black Hawk County | 15 | 2.78% | 134,686 | 131,049 |
| Sioux County | 16 | 2.69% | 36,864 | 35,897 |
| Linn County | 17 | 2.63% | 236,482 | 230,433 |
| Woodbury County | 18 | 2.58% | 108,683 | 105,952 |
| Jefferson County | 19 | 2.5% | 16,091 | 15,699 |
| Wapello County | 20 | 2.5% | 36,209 | 35,327 |
| Crawford County | 21 | 2.22% | 16,858 | 16,492 |
| Mitchell County | 22 | 2.1% | 10,808 | 10,586 |
| Scott County | 23 | 1.72% | 177,625 | 174,617 |
| Guthrie County | 24 | 1.67% | 10,796 | 10,619 |
| Marshall County | 25 | 1.56% | 40,716 | 40,091 |
| Bremer County | 26 | 1.48% | 25,376 | 25,007 |
| Davis County | 27 | 1.47% | 9,249 | 9,115 |
| Jasper County | 28 | 1.38% | 38,339 | 37,818 |
| Boone County | 29 | 1.31% | 27,053 | 26,702 |
| Humboldt County | 30 | 1.31% | 9,723 | 9,597 |
| Benton County | 31 | 1.21% | 25,859 | 25,550 |
| Lucas County | 32 | 1.21% | 8,724 | 8,620 |
| Delaware County | 33 | 1.19% | 17,661 | 17,454 |
| Buena Vista County | 34 | 1.17% | 21,052 | 20,808 |
| Webster County | 35 | 1.16% | 37,421 | 36,991 |
| Washington County | 36 | 1.08% | 22,785 | 22,541 |
| Allamakee County | 37 | 1.04% | 14,216 | 14,069 |
| Plymouth County | 38 | 0.98% | 25,945 | 25,694 |
| Shelby County | 39 | 0.77% | 11,817 | 11,727 |
| Buchanan County | 40 | 0.69% | 20,749 | 20,606 |
| Greene County | 41 | 0.48% | 8,792 | 8,750 |
| Dubuque County | 42 | 0.44% | 99,750 | 99,310 |
| Grundy County | 43 | 0.36% | 12,391 | 12,347 |
| Pottawattamie County | 44 | 0.24% | 93,881 | 93,655 |
| Harrison County | 45 | 0.24% | 14,602 | 14,567 |
| Clay County | 46 | 0.15% | 16,362 | 16,337 |
| Cherokee County | 47 | 0.1% | 11,670 | 11,658 |
| Adair County | 48 | 0.08% | 7,495 | 7,489 |
| Jackson County | 49 | 0.06% | 19,464 | 19,453 |
| Adams County | 50 | 0.05% | 3,712 | 3,710 |
| Mahaska County | 51 | 0.03% | 22,168 | 22,162 |
| Fremont County | 52 | -0.02% | 6,566 | 6,567 |
| Louisa County | 53 | -0.14% | 10,810 | 10,825 |
| Page County | 54 | -0.72% | 15,090 | 15,200 |
| Union County | 55 | -0.73% | 12,039 | 12,128 |
| Des Moines County | 56 | -0.88% | 38,513 | 38,856 |
| Hamilton County | 57 | -0.93% | 14,872 | 15,011 |
| Iowa County | 58 | -0.94% | 16,497 | 16,653 |
| Audubon County | 59 | -1.06% | 5,620 | 5,680 |
| Cerro Gordo County | 60 | -1.12% | 42,539 | 43,021 |
| Clayton County | 61 | -1.24% | 16,823 | 17,034 |
| Van Buren County | 62 | -1.37% | 7,119 | 7,218 |
| Howard County | 63 | -1.38% | 9,366 | 9,497 |
| Pocahontas County | 64 | -1.39% | 6,970 | 7,068 |
| Poweshiek County | 65 | -1.4% | 18,368 | 18,628 |
| Clinton County | 66 | -1.41% | 45,777 | 46,432 |
| Hancock County | 67 | -1.6% | 10,586 | 10,758 |
| Winneshiek County | 68 | -1.69% | 19,713 | 20,051 |
| Wright County | 69 | -1.73% | 12,699 | 12,923 |
| Cedar County | 70 | -1.77% | 18,155 | 18,483 |
| Chickasaw County | 71 | -1.8% | 11,769 | 11,985 |
| Appanoose County | 72 | -1.82% | 12,060 | 12,283 |
| Osceola County | 73 | -2% | 6,076 | 6,200 |
| Palo Alto County | 74 | -2% | 8,813 | 8,993 |
| Worth County | 75 | -2.06% | 7,277 | 7,430 |
| Butler County | 76 | -2.2% | 14,018 | 14,334 |
| Cass County | 77 | -2.33% | 12,810 | 13,115 |
| Tama County | 78 | -2.37% | 16,640 | 17,044 |
| Ringgold County | 79 | -2.39% | 4,532 | 4,643 |
| Fayette County | 80 | -2.42% | 18,978 | 19,448 |
| Carroll County | 81 | -2.59% | 20,197 | 20,734 |
| Kossuth County | 82 | -2.62% | 14,404 | 14,791 |
| Hardin County | 83 | -2.85% | 16,346 | 16,826 |
| Muscatine County | 84 | -3.22% | 41,764 | 43,155 |
| Keokuk County | 85 | -3.41% | 9,671 | 10,012 |
| Calhoun County | 86 | -3.46% | 9,553 | 9,895 |
| Taylor County | 87 | -3.75% | 5,641 | 5,861 |
| Ida County | 88 | -3.83% | 6,760 | 7,029 |
| Decatur County | 89 | -4.23% | 7,406 | 7,733 |
| Montgomery County | 90 | -4.23% | 9,893 | 10,330 |
| Lee County | 91 | -4.23% | 32,110 | 33,529 |
| Clarke County | 92 | -4.32% | 9,310 | 9,730 |
| Emmet County | 93 | -4.39% | 8,932 | 9,342 |
| Monona County | 94 | -5.27% | 8,281 | 8,742 |
| Sac County | 95 | -5.38% | 9,273 | 9,800 |
| Monroe County | 96 | -5.91% | 7,147 | 7,596 |
| Winnebago County | 97 | -5.94% | 10,023 | 10,656 |
| Floyd County | 98 | -7.06% | 14,492 | 15,593 |
| Henry County | 99 | -7.38% | 18,937 | 20,447 |
Iowa's counties show varied growth patterns from 2020 to 2026. Dallas County leads with 3.39% annualized growth, followed by Warren County (1.77%) and Polk County (1.33%). The largest counties are Polk County (533,581), Linn County (236,482), and Scott County (177,625). Of the 99 counties in Iowa, 51 are growing while 48 have experienced population decline. Overall, counties averaged 0% annualized growth, with total population growing by 0.5% annually.
-0.05
-0.025
0
0.025
0.05
0.075