| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Smithville | 1 | 5,743 | 5,047 | 2.19% | 981 | 6 | City |
| Alexandria | 2 | 958 | 915 | 0.74% | 794 | 1 | Town |
| Dowelltown | 3 | 375 | 344 | 1.35% | 499 | 1 | Town |
| Liberty | 4 | 345 | 334 | 0.88% | 299 | 1 | Town |
Smithville is the largest city in DeKalb County, with a population of 5,743.
Liberty is the smallest city in DeKalb County, with a population of 345.
There are 4 cities in DeKalb County, Tennessee.