8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Cairo | 1 | 1,452 | 1,716 | -3.52% | 208 | 7 | City |
| Unity | 2 | 1,392 | 1,402 | 0% | 29 | 48 | Township |
| Olive Branch | 3 | 506 | 610 | -4.53% | 54 | 9 | CDP |
| Tamms | 4 | 356 | 420 | -3.52% | 153 | 2 | Village |
| East Cape Girardeau | 5 | 241 | 285 | -3.6% | 123 | 2 | Village |
| McClure | 6 | 213 | 253 | -3.62% | 139 | 2 | Village |
| Thebes | 7 | 174 | 204 | -3.33% | 100 | 2 | Village |
| Unity | 8 | 68 | 62 | 7.94% | 97 | 1 | CDP |
Cairo is the largest city in Alexander County, with a population of 1,452.
Unity is the smallest city in Alexander County, with a population of 68.
There are 8 cities in Alexander County, Illinois.