| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Demopolis | 1 | 6,537 | 7,141 | -1.57% | 368 | 18 | City |
| Linden | 2 | 1,772 | 1,932 | -1.61% | 495 | 4 | City |
| Thomaston | 3 | 302 | 326 | -1.31% | 150 | 2 | Town |
| Sweet Water | 4 | 211 | 228 | -1.4% | 90 | 2 | Town |
| Yellow Bluff | 5 | 202 | 226 | -1.94% | 323 | 1 | Town |
| Faunsdale | 6 | 80 | 86 | -2.44% | 289 | 0 | Town |
| Myrtlewood | 7 | 65 | 71 | -1.52% | 25 | 3 | Town |
Demopolis is the largest city in Marengo County, with a population of 6,537.
Myrtlewood is the smallest city in Marengo County, with a population of 65.
There are 7 cities in Marengo County, Alabama.