All counties in Iowa
| County Name | Population | State | Rank |
|---|
| Polk County | 430,640 | Iowa | 1 |
| Linn County | 211,226 | Iowa | 2 |
| Scott County | 165,224 | Iowa | 3 |
| Black Hawk County | 131,090 | Iowa | 4 |
| Johnson County | 130,882 | Iowa | 5 |
| Woodbury County | 102,172 | Iowa | 6 |
| Dubuque County | 93,653 | Iowa | 7 |
| Pottawattamie County | 93,158 | Iowa | 8 |
| Story County | 89,542 | Iowa | 9 |
| Dallas County | 66,135 | Iowa | 10 |
| Clinton County | 49,116 | Iowa | 11 |
| Warren County | 46,225 | Iowa | 12 |
| Cerro Gordo County | 44,151 | Iowa | 13 |
| Muscatine County | 42,745 | Iowa | 14 |
| Marshall County | 40,648 | Iowa | 15 |
| Des Moines County | 40,325 | Iowa | 16 |
| Webster County | 38,013 | Iowa | 17 |
| Jasper County | 36,842 | Iowa | 18 |
| Lee County | 35,862 | Iowa | 19 |
| Wapello County | 35,625 | Iowa | 20 |
| Sioux County | 33,704 | Iowa | 21 |
| Marion County | 33,309 | Iowa | 22 |
| Boone County | 26,306 | Iowa | 23 |
| Benton County | 26,076 | Iowa | 24 |
| Plymouth County | 24,986 | Iowa | 25 |
| Bremer County | 24,276 | Iowa | 26 |
| Mahaska County | 22,381 | Iowa | 27 |
| Washington County | 21,704 | Iowa | 28 |
| Winneshiek County | 21,056 | Iowa | 29 |
| Buchanan County | 20,958 | Iowa | 30 |
| Fayette County | 20,880 | Iowa | 31 |
| Carroll County | 20,816 | Iowa | 32 |
| Jones County | 20,638 | Iowa | 33 |
| Buena Vista County | 20,260 | Iowa | 34 |
| Henry County | 20,145 | Iowa | 35 |
| Jackson County | 19,848 | Iowa | 36 |
| Poweshiek County | 18,914 | Iowa | 37 |
| Cedar County | 18,499 | Iowa | 38 |
| Clayton County | 18,129 | Iowa | 39 |
| Tama County | 17,767 | Iowa | 40 |
| Delaware County | 17,764 | Iowa | 41 |
| Hardin County | 17,534 | Iowa | 42 |
| Crawford County | 17,096 | Iowa | 43 |
| Jefferson County | 16,843 | Iowa | 44 |
| Dickinson County | 16,667 | Iowa | 45 |
| Clay County | 16,667 | Iowa | 46 |
| Iowa County | 16,355 | Iowa | 47 |
| Floyd County | 16,303 | Iowa | 48 |
| Page County | 15,932 | Iowa | 49 |
| Madison County | 15,679 | Iowa | 50 |
| Hamilton County | 15,673 | Iowa | 51 |
| Kossuth County | 15,543 | Iowa | 52 |
| Mills County | 15,059 | Iowa | 53 |
| Harrison County | 14,928 | Iowa | 54 |
| Butler County | 14,867 | Iowa | 55 |
| O'brien County | 14,398 | Iowa | 56 |
| Allamakee County | 14,330 | Iowa | 57 |
| Cass County | 13,956 | Iowa | 58 |
| Wright County | 13,229 | Iowa | 59 |
| Appanoose County | 12,887 | Iowa | 60 |
| Union County | 12,534 | Iowa | 61 |
| Grundy County | 12,453 | Iowa | 62 |
| Chickasaw County | 12,439 | Iowa | 63 |
| Shelby County | 12,167 | Iowa | 64 |
| Cherokee County | 12,072 | Iowa | 65 |
| Lyon County | 11,581 | Iowa | 66 |
| Louisa County | 11,387 | Iowa | 67 |
| Hancock County | 11,341 | Iowa | 68 |
| Guthrie County | 10,954 | Iowa | 69 |
| Winnebago County | 10,866 | Iowa | 70 |
| Mitchell County | 10,776 | Iowa | 71 |
| Montgomery County | 10,740 | Iowa | 72 |
| Franklin County | 10,680 | Iowa | 73 |
| Keokuk County | 10,511 | Iowa | 74 |
| Sac County | 10,350 | Iowa | 75 |
| Emmet County | 10,302 | Iowa | 76 |
| Humboldt County | 9,815 | Iowa | 77 |
| Calhoun County | 9,670 | Iowa | 78 |
| Howard County | 9,566 | Iowa | 79 |
| Palo Alto County | 9,421 | Iowa | 80 |
| Greene County | 9,336 | Iowa | 81 |
| Clarke County | 9,286 | Iowa | 82 |
| Monona County | 9,243 | Iowa | 83 |
| Lucas County | 8,898 | Iowa | 84 |
| Davis County | 8,753 | Iowa | 85 |
| Decatur County | 8,457 | Iowa | 86 |
| Monroe County | 7,970 | Iowa | 87 |
| Adair County | 7,682 | Iowa | 88 |
| Worth County | 7,598 | Iowa | 89 |
| Van Buren County | 7,570 | Iowa | 90 |
| Fremont County | 7,441 | Iowa | 91 |
| Pocahontas County | 7,310 | Iowa | 92 |
| Ida County | 7,089 | Iowa | 93 |
| Osceola County | 6,462 | Iowa | 94 |
| Wayne County | 6,403 | Iowa | 95 |
| Taylor County | 6,317 | Iowa | 96 |
| Audubon County | 6,119 | Iowa | 97 |
| Ringgold County | 5,131 | Iowa | 98 |
| Adams County | 4,029 | Iowa | 99 |