Iowa Counties by Population (2025)
2025 Pop.
50K
100K
150K
200K
250K
300K
350K
400K
450K
500K
Top 5 Most Populous Counties
524,883
234,122
176,613
161,958
133,517
99 Counties
| County | 2025 Pop. ↓ | Area (mi²) | Density | Change (2020) |
|---|---|---|---|---|
| Polk County | 524,883 | 572 | 918 | 6.46% |
| Linn County | 234,122 | 717 | 327 | 1.6% |
| Scott County | 176,613 | 458 | 386 | 1.14% |
| Johnson County | 161,958 | 613 | 264 | 5.82% |
| Black Hawk County | 133,517 | 566 | 236 | 1.88% |
| Dallas County | 119,093 | 588 | 203 | 18.45% |
| Woodbury County | 107,970 | 873 | 124 | 1.9% |
| Story County | 103,495 | 573 | 181 | 4.91% |
| Dubuque County | 99,496 | 608 | 164 | 0.19% |
| Pottawattamie County | 93,705 | 951 | 99 | 0.05% |
| Warren County | 57,388 | 570 | 101 | 9.12% |
| Clinton County | 45,896 | 695 | 66 | -1.15% |
| Cerro Gordo County | 42,516 | 568 | 75 | -1.17% |
| Muscatine County | 41,948 | 437 | 96 | -2.8% |
| Marshall County | 40,554 | 573 | 71 | 1.15% |
| Des Moines County | 38,462 | 416 | 92 | -1.01% |
| Jasper County | 38,223 | 730 | 52 | 1.07% |
| Webster County | 37,165 | 716 | 52 | 0.47% |
| Sioux County | 36,709 | 768 | 48 | 2.26% |
| Wapello County | 35,945 | 432 | 83 | 1.75% |
| Marion County | 34,378 | 554 | 62 | 2.89% |
| Lee County | 32,243 | 518 | 62 | -3.84% |
| Boone County | 26,891 | 570 | 47 | 0.71% |
| Plymouth County | 25,885 | 863 | 30 | 0.74% |
| Benton County | 25,829 | 716 | 36 | 1.09% |
| Bremer County | 25,352 | 435 | 58 | 1.38% |
| Washington County | 22,708 | 569 | 40 | 0.74% |
| Mahaska County | 22,101 | 571 | 39 | -0.28% |
| Jones County | 21,315 | 576 | 37 | 3.2% |
| Buena Vista County | 20,934 | 575 | 36 | 0.61% |
| Buchanan County | 20,741 | 571 | 36 | 0.66% |
| Carroll County | 20,302 | 569 | 36 | -2.08% |
| Winneshiek County | 19,718 | 690 | 29 | -1.66% |
| Jackson County | 19,427 | 636 | 31 | -0.13% |
| Henry County | 19,149 | 434 | 44 | -6.35% |
| Fayette County | 19,065 | 731 | 26 | -1.97% |
| Poweshiek County | 18,411 | 585 | 31 | -1.16% |
| Dickinson County | 18,229 | 381 | 48 | 2.57% |
| Cedar County | 18,193 | 579 | 31 | -1.57% |
| Delaware County | 17,635 | 578 | 31 | 1.04% |
| Madison County | 17,323 | 561 | 31 | 4.18% |
| Clayton County | 16,877 | 778 | 22 | -0.92% |
| Tama County | 16,689 | 721 | 23 | -2.08% |
| Crawford County | 16,618 | 714 | 23 | 0.76% |
| Iowa County | 16,460 | 586 | 28 | -1.16% |
| Clay County | 16,418 | 567 | 29 | 0.5% |
| Hardin County | 16,405 | 569 | 29 | -2.5% |
| Jefferson County | 15,936 | 436 | 37 | 1.51% |
| Page County | 15,064 | 535 | 28 | -0.89% |
| Hamilton County | 14,864 | 577 | 26 | -0.98% |
| Mills County | 14,792 | 437 | 34 | 2.59% |
| Floyd County | 14,750 | 501 | 29 | -5.41% |
| Harrison County | 14,614 | 697 | 21 | 0.32% |
| O'Brien County | 14,453 | 573 | 25 | 2.15% |
| Kossuth County | 14,406 | 973 | 15 | -2.6% |
| Allamakee County | 14,200 | 639 | 22 | 0.93% |
| Butler County | 14,087 | 580 | 24 | -1.72% |
| Cass County | 12,917 | 564 | 23 | -1.51% |
| Wright County | 12,714 | 580 | 22 | -1.62% |
| Lyon County | 12,468 | 588 | 21 | 4.57% |
| Grundy County | 12,398 | 502 | 25 | 0.41% |
| Appanoose County | 12,083 | 497 | 24 | -1.63% |
| Union County | 11,997 | 424 | 28 | -1.08% |
| Shelby County | 11,819 | 591 | 20 | 0.78% |
| Chickasaw County | 11,744 | 504 | 23 | -2.01% |
| Cherokee County | 11,664 | 577 | 20 | 0.05% |
| Guthrie County | 10,785 | 591 | 18 | 1.56% |
| Louisa County | 10,720 | 402 | 27 | -0.97% |
| Mitchell County | 10,720 | 469 | 23 | 1.27% |
| Hancock County | 10,601 | 571 | 19 | -1.46% |
| Winnebago County | 10,203 | 400 | 26 | -4.25% |
| Franklin County | 10,153 | 582 | 17 | 1.58% |
| Montgomery County | 9,978 | 424 | 24 | -3.41% |
| Keokuk County | 9,763 | 579 | 17 | -2.49% |
| Humboldt County | 9,670 | 434 | 22 | 0.76% |
| Calhoun County | 9,632 | 570 | 17 | -2.66% |
| Clarke County | 9,417 | 431 | 22 | -3.22% |
| Sac County | 9,403 | 575 | 16 | -4.05% |
| Howard County | 9,363 | 473 | 20 | -1.41% |
| Davis County | 9,221 | 502 | 18 | 1.16% |
| Emmet County | 9,047 | 396 | 23 | -3.16% |
| Palo Alto County | 8,811 | 564 | 16 | -2.02% |
| Lucas County | 8,741 | 431 | 20 | 1.4% |
| Greene County | 8,727 | 570 | 15 | -0.26% |
| Monona County | 8,355 | 694 | 12 | -4.43% |
| Decatur County | 7,531 | 532 | 14 | -2.61% |
| Adair County | 7,463 | 569 | 13 | -0.35% |
| Worth County | 7,292 | 400 | 18 | -1.86% |
| Monroe County | 7,260 | 434 | 17 | -4.42% |
| Van Buren County | 7,168 | 485 | 15 | -0.69% |
| Pocahontas County | 6,988 | 577 | 12 | -1.13% |
| Ida County | 6,785 | 432 | 16 | -3.47% |
| Wayne County | 6,702 | 525 | 13 | 3.08% |
| Fremont County | 6,530 | 511 | 13 | -0.56% |
| Osceola County | 6,056 | 399 | 15 | -2.32% |
| Taylor County | 5,733 | 532 | 11 | -2.18% |
| Audubon County | 5,591 | 443 | 13 | -1.57% |
| Ringgold County | 4,570 | 535 | 9 | -1.57% |
| Adams County | 3,659 | 423 | 9 | -1.37% |
Overview of Iowa Counties
There are 99 counties in Iowa.
Polk County is the largest county in the state, with a population of 524,883. The most recent census shows that its population has increased by 0.06% since the previous census.
A number of other Iowa counties also boast relatively large populations for their state, though not able to match the density of Polk County:
- Linn County : 234,122
- Scott County : 176,613
Iowa Counties with the Fewest Residents
The smallest county in Iowa is Adams County , with a population of just 3,659. This total represents a decrease of 0.0% since the last census count was performed.
Other small counties include:
- Ringgold County : 4,570
- Audubon County : 5,591
- Taylor County : 5,733
Iowa Counties with Rapid Growth
Dallas County , with its sizeable population of 119,093, has shown the largest population growth, with an increase of 0.2% since the last census.
Polk County has also had relatively high population growth of 0.06% with 524,883 residents.
On the other hand, Henry County has had the largest decrease in population, with its 19,149 current residents totalling 0.1% less than the previous census.
Sources
- US Census State Population Estimates - Most recent state estimates from the Census Bureau's Population Estimates Program
- US Census County Population Estimates - Most recent county estimates from the Census Bureau's Population Estimates Program
- American Community Survey (2009 - 2013)
- Census QuickFacts
- Historical Populations of States and Counties (1790 - 1990)