24 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Thief River Falls | 1 | 8,763 | 8,842 | -0.18% | 1,460 | 6 | City |
| Rocksbury | 2 | 1,050 | 1,092 | 0% | 31 | 33 | Township |
| North | 3 | 611 | 640 | -0.33% | 27 | 23 | Township |
| Smiley | 4 | 586 | 626 | -0.68% | 16 | 36 | Township |
| Norden | 5 | 356 | 365 | -0.56% | 13 | 28 | Township |
| Sanders | 6 | 288 | 302 | -0.69% | 8 | 36 | Township |
| St. Hilaire | 7 | 251 | 273 | -1.95% | 321 | 1 | City |
| Highlanding | 8 | 187 | 200 | -1.06% | 5 | 36 | Township |
| River Falls | 9 | 179 | 190 | -0.56% | 8 | 23 | Township |
| Silverton | 10 | 172 | 187 | -1.71% | 6 | 27 | Township |
| Kratka | 11 | 133 | 141 | -0.75% | 4 | 36 | Township |
| Deer Park | 12 | 121 | 127 | 0% | 5 | 23 | Township |
| Goodridge | 13 | 106 | 111 | -0.93% | 564 | 0 | City |
| Star | 14 | 95 | 101 | -1.04% | 3 | 36 | Township |
| Numedal | 15 | 94 | 96 | 0% | 3 | 28 | Township |
| Wyandotte | 16 | 89 | 94 | 0% | 4 | 23 | Township |
| Cloverleaf | 17 | 88 | 93 | 0% | 3 | 27 | Township |
| Reiner | 18 | 88 | 93 | 0% | 3 | 27 | Township |
| Goodridge | 19 | 74 | 78 | 0% | 3 | 27 | Township |
| Hickory | 20 | 64 | 68 | 0% | 2 | 35 | Township |
| Black River | 21 | 62 | 67 | -1.59% | 3 | 24 | Township |
| Polk Centre | 22 | 58 | 63 | -1.69% | 2 | 24 | Township |
| Bray | 23 | 50 | 53 | 0% | 1 | 36 | Township |
| Mayfield | 24 | 44 | 48 | -2.22% | 2 | 23 | Township |
Thief River Falls is the largest city in Pennington County, with a population of 8,763.
Mayfield is the smallest city in Pennington County, with a population of 44.
There are 24 cities in Pennington County, Minnesota.