| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Wapello | 1 | 1,962 | 2,082 | -0.86% | 1,510 | 1 | City |
| Columbus Junction | 2 | 1,758 | 1,849 | -0.79% | 819 | 2 | City |
| Morning Sun | 3 | 675 | 750 | -1.89% | 869 | 1 | City |
| Grandview | 4 | 411 | 435 | -0.96% | 1,803 | 0 | City |
| Columbus City | 5 | 372 | 386 | -0.53% | 1,550 | 0 | City |
| Letts | 6 | 348 | 362 | -0.57% | 614 | 1 | City |
| Fredonia | 7 | 209 | 219 | -0.95% | 1,384 | 0 | City |
| Oakville | 8 | 192 | 198 | -0.52% | 460 | 0 | City |
| Cotter | 9 | 38 | 39 | -2.56% | 388 | 0 | City |
Wapello is the largest city in Louisa County, with a population of 1,962.
Cotter is the smallest city in Louisa County, with a population of 38.
There are 9 cities in Louisa County, Iowa.