| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rolla | 1 | 20,723 | 19,912 | 0.66% | 1,709 | 12 | City |
| St. James | 2 | 3,925 | 3,897 | 0% | 919 | 4 | City |
| Newburg | 3 | 330 | 335 | -0.3% | 512 | 1 | City |
| Edgar Springs | 4 | 196 | 197 | 0% | 418 | 0 | City |
Rolla is the largest city in Phelps County, with a population of 20,723.
Edgar Springs is the smallest city in Phelps County, with a population of 196.
There are 4 cities in Phelps County, Missouri.