| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sioux City | 1 | 86,493 | 85,893 | 0.16% | 1,456 | 59 | City |
| Sergeant Bluff | 2 | 5,401 | 5,009 | 1.45% | 1,817 | 3 | City |
| Moville | 3 | 1,710 | 1,691 | 0.12% | 1,863 | 1 | City |
| Sloan | 4 | 1,084 | 1,048 | 0.56% | 1,875 | 1 | City |
| Lawton | 5 | 947 | 945 | 0% | 1,315 | 1 | City |
| Correctionville | 6 | 755 | 763 | -0.13% | 1,256 | 1 | City |
| Anthon | 7 | 531 | 541 | -0.38% | 753 | 1 | City |
| Pierson | 8 | 325 | 335 | -0.61% | 684 | 0 | City |
| Danbury | 9 | 306 | 317 | -0.65% | 756 | 0 | City |
| Salix | 10 | 305 | 300 | 0% | 180 | 2 | City |
| Bronson | 11 | 294 | 297 | -0.34% | 850 | 0 | City |
| Hornick | 12 | 252 | 258 | -0.4% | 821 | 0 | City |
| Cushing | 13 | 223 | 232 | -0.89% | 701 | 0 | City |
| Smithland | 14 | 183 | 186 | -0.54% | 570 | 0 | City |
| Oto | 15 | 70 | 72 | -1.41% | 260 | 0 | City |
Sioux City is the largest city in Woodbury County, with a population of 86,493.
Oto is the smallest city in Woodbury County, with a population of 70.
There are 15 cities in Woodbury County, Iowa.