18 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Polk | 1 | 13,832 | 14,262 | -0.66% | 115 | 120 | Township |
| Polk | 2 | 13,832 | 14,041 | -0.66% | 115 | 120 | Township |
| Bolivar | 3 | 11,735 | 10,770 | 1.61% | 1,426 | 8 | City |
| Bolivar | 4 | 11,735 | 10,804 | 1.61% | 1,426 | 8 | City |
| Humansville | 5 | 945 | 911 | 0.64% | 757 | 1 | City |
| Humansville | 6 | 945 | 913 | 0.64% | 757 | 1 | City |
| Polk | 7 | 722 | 732 | -0.28% | 13 | 57 | Township |
| Polk | 8 | 722 | 730 | -0.28% | 13 | 57 | Township |
| Fair Play | 9 | 453 | 434 | 0.67% | 1,061 | 0 | City |
| Fair Play | 10 | 453 | 435 | 0.67% | 1,061 | 0 | City |
| Morrisville | 11 | 401 | 384 | 0.75% | 621 | 1 | Town |
| Morrisville | 12 | 401 | 385 | 0.75% | 621 | 1 | Town |
| Halfway | 13 | 154 | 147 | 0.65% | 77 | 2 | Village |
| Halfway | 14 | 154 | 148 | 0.65% | 77 | 2 | Village |
| Flemington | 15 | 114 | 110 | 0% | 344 | 0 | Village |
| Flemington | 16 | 114 | 111 | 0% | 344 | 0 | Village |
| Aldrich | 17 | 69 | 66 | 0% | 483 | 0 | Village |
| Aldrich | 18 | 69 | 66 | 0% | 483 | 0 | Village |
Polk is the largest city in Polk County, with a population of 13,832.
Aldrich is the smallest city in Polk County, with a population of 69.
There are 18 cities in Polk County, Missouri.