6 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Dallas | 1 | 18,082 | 16,987 | 1.23% | 3,682 | 4.91 | City |
| Monmouth | 2 | 11,352 | 11,147 | 0.36% | 5,070 | 2.24 | City |
| Independence | 3 | 10,423 | 9,983 | 0.85% | 3,482 | 2.99 | City |
| Grand Ronde | 4 | 1,347 | 1,479 | -1.54% | 70 | 19.20 | CDP |
| Falls City | 5 | 1,072 | 1,056 | 0.28% | 892 | 1.20 | City |
| Fort Hill | 6 | 49 | 101 | -9.26% | 34 | 1.43 | CDP |
Dallas is the largest city in Polk County, with a population of 18,082.
Fort Hill is the smallest city in Polk County, with a population of 49.
There are 6 cities in Polk County, Oregon.