21 cities
| City | Rank | 2025 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Berlin | 1 | 9,208 | 9,406 | -0.43% | 150 | 61 | City |
| Berlin | 2 | 9,192 | 9,406 | -0.61% | 150 | 61 | City |
| Lancaster | 3 | 3,201 | 3,211 | -0.34% | 64 | 50 | Town |
| Gorham | 4 | 2,667 | 2,692 | -0.22% | 84 | 32 | Town |
| Whitefield | 5 | 2,521 | 2,494 | -0.28% | 74 | 34 | Town |
| Colebrook | 6 | 2,098 | 2,081 | -0.1% | 52 | 41 | Town |
| Northumberland | 7 | 2,096 | 2,125 | -0.52% | 59 | 36 | Town |
| Milan | 8 | 1,351 | 1,357 | -0.59% | 21 | 64 | Town |
| Jefferson | 9 | 1,054 | 1,047 | -0.57% | 21 | 50 | Town |
| Dalton | 10 | 905 | 927 | -0.77% | 33 | 28 | Town |
| Carroll | 11 | 847 | 818 | 0.95% | 17 | 50 | Town |
| Pittsburg | 12 | 842 | 805 | 0.6% | 3 | 281 | Town |
| Stewartstown | 13 | 771 | 807 | -0.52% | 17 | 46 | Town |
| Columbia | 14 | 668 | 662 | 0.15% | 11 | 61 | Town |
| Stratford | 15 | 647 | 661 | -0.61% | 8 | 79 | Town |
| Stark | 16 | 464 | 475 | -0.64% | 8 | 59 | Town |
| Shelburne | 17 | 361 | 354 | 0.28% | 8 | 48 | Town |
| Randolph | 18 | 327 | 329 | 0% | 7 | 47 | Town |
| Dummer | 19 | 314 | 305 | 0.32% | 7 | 48 | Town |
| Errol | 20 | 291 | 299 | -0.68% | 5 | 60 | Town |
| Clarksville | 21 | 283 | 290 | -0.7% | 5 | 60 | Town |
Berlin is the largest city in Coos County, with a population of 9,208.
Clarksville is the smallest city in Coos County, with a population of 283.
There are 21 cities in Coos County, New Hampshire.