8 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Rolla | 1 | 20,844 | 19,929 | 0.89% | 1,719 | 12 | City |
| Rolla | 2 | 20,844 | 19,921 | 0.89% | 1,719 | 12 | City |
| St. James | 3 | 3,936 | 3,927 | 0.1% | 921 | 4 | City |
| St. James | 4 | 3,936 | 3,913 | 0.1% | 921 | 4 | City |
| Newburg | 5 | 336 | 334 | 0% | 521 | 1 | City |
| Newburg | 6 | 336 | 333 | 0% | 521 | 1 | City |
| Edgar Springs | 7 | 203 | 200 | 0% | 433 | 0 | City |
| Edgar Springs | 8 | 203 | 200 | 0% | 433 | 0 | City |
Rolla is the largest city in Phelps County, with a population of 20,844.
Edgar Springs is the smallest city in Phelps County, with a population of 203.
There are 8 cities in Phelps County, Missouri.