This is less than a one percent rise in Polk County’s population, from 492,769 in 2020 to 496,844 in 2021.
Polk County had the largest population in Iowa in 2021.
The US Census Bureau found more than 73 percent of counties in the US saw a natural decrease in population in 2021. This is up from a 55.5 percent increase in 2020.
The Midwest suffered the most sustained population decreases, with many counties along the US East Coast and through the Rocky Mountains seeing increases.
The US population continues to grow, though at a slower rate than before.
Iowa Counties By Population Change from 2020 to 2021
| County | 2020 Estimated Population | 2021 Estimated Population | % Change in Population From Year to Year |
|---|---|---|---|
| Dallas County | 100,486 | 103,796 | 3.3% |
| Warren County | 52,548 | 53,402 | 1.6% |
| Johnson County | 152,984 | 154,748 | 1.2% |
| Lucas County | 8,615 | 8,710 | 1.1% |
| Madison County | 16,626 | 16,773 | 0.9% |
| Story County | 98,615 | 99,472 | 0.9% |
| Adair County | 7,477 | 7,541 | 0.9% |
| Harrison County | 14,546 | 14,669 | 0.8% |
| Polk County | 492,769 | 496,844 | 0.8% |
| Lyon County | 11,917 | 12,011 | 0.8% |
| Jones County | 20,647 | 20,805 | 0.8% |
| Clay County | 16,333 | 16,440 | 0.7% |
| Decatur County | 7,610 | 7,659 | 0.6% |
| Benton County | 25,536 | 25,691 | 0.6% |
| Shelby County | 11,699 | 11,770 | 0.6% |
| Clarke County | 9,726 | 9,785 | 0.6% |
| Dickinson County | 17,747 | 17,851 | 0.6% |
| Van Buren County | 7,204 | 7,243 | 0.5% |
| Webster County | 36,954 | 37,147 | 0.5% |
| Bremer County | 24,974 | 25,081 | 0.4% |
| Mills County | 14,405 | 14,465 | 0.4% |
| Humboldt County | 9,595 | 9,634 | 0.4% |
| Monroe County | 7,582 | 7,610 | 0.4% |
| Buchanan County | 20,586 | 20,657 | 0.3% |
| Davis County | 9,109 | 9,138 | 0.3% |
| Delaware County | 17,458 | 17,510 | 0.3% |
| Calhoun County | 9,886 | 9,915 | 0.3% |
| Grundy County | 12,312 | 12,347 | 0.3% |
| Butler County | 14,311 | 14,332 | 0.1% |
| Boone County | 26,691 | 26,723 | 0.1% |
| Taylor County | 5,861 | 5,868 | 0.1% |
| Page County | 15,180 | 15,197 | 0.1% |
| Fremont County | 6,560 | 6,567 | 0.1% |
| Clinton County | 46,418 | 46,463 | 0.1% |
| Sioux County | 35,869 | 35,893 | 0.1% |
| Winnebago County | 10,650 | 10,656 | 0.1% |
| Clayton County | 16,996 | 16,998 | 0% |
| Marion County | 33,377 | 33,380 | 0% |
| Ringgold County | 4,639 | 4,639 | 0% |
| Pocahontas County | 7,075 | 7,074 | 0% |
| Wayne County | 6,509 | 6,508 | 0% |
| Buena Vista County | 20,776 | 20,771 | 0% |
| Carroll County | 20,702 | 20,692 | 0% |
| Jefferson County | 15,659 | 15,647 | -0.1% |
| Washington County | 22,511 | 22,491 | -0.1% |
| Howard County | 9,487 | 9,478 | -0.1% |
| Jasper County | 37,802 | 37,764 | -0.1% |
| Emmet County | 9,332 | 9,321 | -0.1% |
| Plymouth County | 25,681 | 25,650 | -0.1% |
| Henry County | 20,412 | 20,387 | -0.1% |
| Montgomery County | 10,335 | 10,322 | -0.1% |
| Scott County | 174,488 | 174,170 | -0.2% |
| Appanoose County | 12,282 | 12,257 | -0.2% |
| Woodbury County | 105,829 | 105,607 | -0.2% |
| Wapello County | 35,341 | 35,256 | -0.2% |
| Mitchell County | 10,582 | 10,555 | -0.3% |
| Pottawattamie County | 93,560 | 93,304 | -0.3% |
| Poweshiek County | 18,643 | 18,586 | -0.3% |
| Franklin County | 9,983 | 9,952 | -0.3% |
| Greene County | 8,746 | 8,717 | -0.3% |
| Jackson County | 19,437 | 19,368 | -0.4% |
| Sac County | 9,791 | 9,752 | -0.4% |
| Cass County | 13,104 | 13,050 | -0.4% |
| Guthrie County | 10,612 | 10,567 | -0.4% |
| Cedar County | 18,495 | 18,410 | -0.5% |
| Black Hawk County | 130,980 | 130,368 | -0.5% |
| Osceola County | 6,189 | 6,159 | -0.5% |
| Marshall County | 40,059 | 39,853 | -0.5% |
| Dubuque County | 99,229 | 98,718 | -0.5% |
| Louisa County | 10,806 | 10,749 | -0.5% |
| Worth County | 7,425 | 7,385 | -0.5% |
| Linn County | 230,263 | 228,939 | -0.6% |
| Cerro Gordo County | 42,965 | 42,706 | -0.6% |
| Palo Alto County | 8,961 | 8,906 | -0.6% |
| Audubon County | 5,671 | 5,635 | -0.6% |
| Union County | 12,097 | 12,018 | -0.7% |
| Iowa County | 16,679 | 16,568 | -0.7% |
| Hardin County | 16,821 | 16,708 | -0.7% |
| Chickasaw County | 11,970 | 11,887 | -0.7% |
| Winneshiek County | 20,031 | 19,892 | -0.7% |
| Fayette County | 19,399 | 19,258 | -0.7% |
| Ida County | 7,007 | 6,956 | -0.7% |
| Mahaska County | 22,148 | 21,984 | -0.7% |
| Keokuk County | 9,995 | 9,914 | -0.8% |
| Hancock County | 10,757 | 10,663 | -0.9% |
| Des Moines County | 38,831 | 38,491 | -0.9% |
| Hamilton County | 15,020 | 14,887 | -0.9% |
| Lee County | 33,512 | 33,215 | -0.9% |
| Floyd County | 15,552 | 15,413 | -0.9% |
| O'Brien County | 14,154 | 14,015 | -1% |
| Muscatine County | 43,113 | 42,688 | -1% |
| Wright County | 12,914 | 12,785 | -1% |
| Allamakee County | 14,067 | 13,926 | -1% |
| Cherokee County | 11,632 | 11,503 | -1.1% |
| Tama County | 17,072 | 16,867 | -1.2% |
| Adams County | 3,697 | 3,641 | -1.5% |
| Crawford County | 16,453 | 16,193 | -1.6% |
| Kossuth County | 14,786 | 14,529 | -1.7% |
| Monona County | 8,742 | 8,574 | -1.9% |
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