| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Princeton | 1 | 962 | 1,004 | -0.82% | 605 | 2 | City |
| Mercer | 2 | 252 | 262 | -0.79% | 685 | 0 | Town |
| South Lineville | 3 | 13 | 14 | -7.14% | 241 | 0 | Town |
Princeton is the largest city in Mercer County, with a population of 962.
South Lineville is the smallest city in Mercer County, with a population of 13.
There are 3 cities in Mercer County, Missouri.