| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Newcastle | 1 | 16,079 | 11,171 | 5.8% | 268 | 60 | City |
| Blanchard | 2 | 10,252 | 8,883 | 2.39% | 337 | 30 | City |
| Purcell | 3 | 7,105 | 6,645 | 1.07% | 466 | 15 | City |
| Dibble | 4 | 1,014 | 878 | 2.22% | 136 | 7 | Town |
| Washington | 5 | 795 | 705 | 1.92% | 549 | 1 | Town |
| Wayne | 6 | 702 | 625 | 1.74% | 1,847 | 0 | Town |
| Byars | 7 | 213 | 189 | 1.91% | 139 | 2 | Town |
Newcastle is the largest city in McClain County, with a population of 16,079.
Byars is the smallest city in McClain County, with a population of 213.
There are 7 cities in McClain County, Oklahoma.