16 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Sioux City | 1 | 87,121 | 85,888 | 0.28% | 1,480 | 59 | City |
| Sergeant Bluff | 2 | 5,416 | 5,010 | 1.52% | 1,822 | 3 | City |
| Moville | 3 | 1,710 | 1,693 | 0.18% | 1,863 | 1 | City |
| Sloan | 4 | 1,085 | 1,049 | 0.65% | 1,877 | 1 | City |
| Lawton | 5 | 950 | 944 | 0.11% | 1,319 | 1 | City |
| Correctionville | 6 | 758 | 760 | -0.13% | 1,261 | 1 | City |
| Anthon | 7 | 532 | 539 | -0.37% | 755 | 1 | City |
| Pierson | 8 | 333 | 340 | -0.6% | 701 | 0 | City |
| Danbury | 9 | 314 | 319 | -0.32% | 775 | 0 | City |
| Salix | 10 | 303 | 300 | 0% | 178 | 2 | City |
| Bronson | 11 | 293 | 296 | -0.34% | 847 | 0 | City |
| Hornick | 12 | 254 | 257 | -0.39% | 827 | 0 | City |
| Cushing | 13 | 223 | 230 | -0.89% | 701 | 0 | City |
| Smithland | 14 | 183 | 186 | -0.54% | 570 | 0 | City |
| Climbing Hill | 15 | 89 | 86 | 7.23% | 69 | 1 | CDP |
| Oto | 16 | 70 | 72 | -1.41% | 260 | 0 | City |
Sioux City is the largest city in Woodbury County, with a population of 87,121.
Oto is the smallest city in Woodbury County, with a population of 70.
There are 16 cities in Woodbury County, Iowa.