7 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Kirksville | 1 | 18,002 | 17,519 | 0.45% | 1,251 | 14 | City |
| Greentop | 2 | 392 | 385 | 0.26% | 480 | 1 | City |
| Novinger | 3 | 384 | 383 | 0% | 488 | 1 | City |
| Brashear | 4 | 241 | 240 | 0% | 689 | 0 | City |
| Millard | 5 | 82 | 78 | 1.23% | 683 | 0 | Village |
| Gibbs | 6 | 76 | 76 | 0% | 306 | 0 | Village |
| South Gifford | 7 | 21 | 21 | 0% | 102 | 0 | Village |
Kirksville is the largest city in Adair County, with a population of 18,002.
South Gifford is the smallest city in Adair County, with a population of 21.
There are 7 cities in Adair County, Missouri.