8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Demopolis | 1 | 6,627 | 7,142 | -1.53% | 373 | 17.74 | City |
| Linden | 2 | 1,796 | 1,926 | -1.43% | 502 | 3.58 | City |
| Thomaston | 3 | 313 | 325 | -0.63% | 155 | 2.01 | Town |
| Sweet Water | 4 | 213 | 228 | -1.39% | 91 | 2.35 | Town |
| Yellow Bluff | 5 | 209 | 226 | -1.42% | 334 | 0.63 | Town |
| Faunsdale | 6 | 82 | 86 | -1.2% | 296 | 0.28 | Town |
| Myrtlewood | 7 | 67 | 71 | -1.47% | 26 | 2.60 | Town |
| Nanafalia | 8 | 29 | 32 | 7.41% | 13 | 2.17 | CDP |
Demopolis is the largest city in Marengo County, with a population of 6,627.
Nanafalia is the smallest city in Marengo County.
There are 8 cities in Marengo County, Alabama.