The graph below ranks each Iowa County by total residents according to the 2012 census estimates.
Iowa total population by county
| County | Total Population |
| Polk |  444,009 |
| Linn | 215,185 |
| Scott | 168,676 |
| Johnson | 136,428 |
| Black Hawk | 131,638 |
| Woodbury | 102,220 |
| Dubuque | 95,062 |
| Pottawattamie | 92,817 |
| Story | 91,630 |
| Dallas | 72,098 |
| Clinton | 48,708 |
| Warren | 46,926 |
| Cerro Gordo | 43,758 |
| Muscatine | 42,859 |
| Marshall | 41,078 |
| Des Moines | 40,305 |
| Webster | 37,207 |
| Jasper | 36,598 |
| Lee | 35,660 |
| Wapello | 35,381 |
| Sioux | 34,370 |
| Marion | 33,322 |
| Boone | 26,217 |
| Benton | 25,849 |
| Plymouth | 24,912 |
| Bremer | 24,472 |
| Mahaska | 22,447 |
| Washington | 21,942 |
| Winneshiek | 21,061 |
| Buchanan | 20,946 |
| Fayette | 20,822 |
| Carroll | 20,653 |
| Jones | 20,594 |
| Buena Vista | 20,562 |
| Henry | 20,097 |
| Jackson | 19,705 |
| Poweshiek | 18,728 |
| Cedar | 18,440 |
| Clayton | 17,911 |
| Delaware | 17,604 |
| Tama | 17,542 |
| Hardin | 17,376 |
| Crawford | 17,301 |
| Dickinson | 16,946 |
| Jefferson | 16,777 |
| Clay | 16,591 |
| Iowa | 16,223 |
| Floyd | 16,112 |
| Page | 15,746 |
| Madison | 15,628 |
| Kossuth | 15,352 |
| Hamilton | 15,300 |
| Butler | 14,976 |
| Mills | 14,876 |
| Harrison | 14,532 |
| Allamakee | 14,203 |
| O'Brien | 14,185 |
| Cass | 13,716 |
| Wright | 12,997 |
| Appanoose | 12,715 |
| Union | 12,584 |
| Grundy | 12,426 |
| Chickasaw | 12,284 |
| Shelby | 12,089 |
| Cherokee | 11,992 |
| Lyon | 11,772 |
| Louisa | 11,305 |
| Hancock | 11,168 |
| Guthrie | 10,782 |
| Mitchell | 10,727 |
| Winnebago | 10,629 |
| Montgomery | 10,552 |
| Franklin | 10,540 |
| Keokuk | 10,390 |
| Sac | 10,166 |
| Emmet | 9,997 |
| Calhoun | 9,928 |
| Humboldt | 9,742 |
| Howard | 9,598 |
| Clarke | 9,389 |
| Palo Alto | 9,298 |
| Greene | 9,172 |
| Monona | 9,165 |
| Lucas | 8,769 |
| Davis | 8,716 |
| Decatur | 8,237 |
| Monroe | 8,080 |
| Adair | 7,515 |
| Worth | 7,507 |
| Van Buren | 7,459 |
| Pocahontas | 7,166 |
| Fremont | 7,142 |
| Ida | 7,110 |
| Wayne | 6,362 |
| Taylor | 6,206 |
| Osceola | 6,199 |
| Audubon | 5,876 |
| Ringgold | 5,102 |
| Adams | 3,907 |