5 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Chariton | 1 | 4,301 | 4,186 | 0.54% | 1,141 | 4 | City |
| Russell | 2 | 475 | 472 | 0% | 463 | 1 | City |
| Lucas | 3 | 176 | 173 | 0% | 179 | 1 | City |
| Williamson | 4 | 127 | 119 | 0.79% | 333 | 0 | City |
| Derby | 5 | 89 | 88 | 0% | 349 | 0 | City |
Chariton is the largest city in Lucas County, with a population of 4,301.
Derby is the smallest city in Lucas County, with a population of 89.
There are 5 cities in Lucas County, Iowa.