8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cairo | 1 | 1,474 | 1,716 | -3.22% | 211 | 7 | City |
| Unity | 2 | 1,378 | 1,406 | -0.58% | 29 | 48 | Township |
| Olive Branch | 3 | 506 | 610 | -4.53% | 54 | 9 | CDP |
| Tamms | 4 | 361 | 419 | -3.22% | 155 | 2 | Village |
| East Cape Girardeau | 5 | 244 | 286 | -3.56% | 124 | 2 | Village |
| McClure | 6 | 217 | 252 | -3.13% | 142 | 2 | Village |
| Thebes | 7 | 176 | 205 | -3.3% | 101 | 2 | Village |
| Unity | 8 | 68 | 62 | 7.94% | 97 | 1 | CDP |
Cairo is the largest city in Alexander County, with a population of 1,474.
Unity is the smallest city in Alexander County, with a population of 68.
There are 8 cities in Alexander County, Illinois.