20 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Berlin | 1 | 9,136 | 9,406 | -0.61% | 149 | 61 | City |
| Lancaster | 2 | 3,190 | 3,211 | -0.34% | 64 | 50 | Town |
| Gorham | 3 | 2,661 | 2,692 | -0.22% | 84 | 32 | Town |
| Whitefield | 4 | 2,514 | 2,494 | -0.28% | 73 | 34 | Town |
| Colebrook | 5 | 2,096 | 2,081 | -0.1% | 52 | 41 | Town |
| Northumberland | 6 | 2,085 | 2,125 | -0.52% | 58 | 36 | Town |
| Milan | 7 | 1,343 | 1,357 | -0.59% | 21 | 64 | Town |
| Jefferson | 8 | 1,048 | 1,047 | -0.57% | 21 | 50 | Town |
| Dalton | 9 | 898 | 927 | -0.77% | 33 | 28 | Town |
| Carroll | 10 | 855 | 818 | 0.94% | 17 | 50 | Town |
| Pittsburg | 11 | 847 | 805 | 0.59% | 3 | 281 | Town |
| Stewartstown | 12 | 767 | 807 | -0.52% | 17 | 46 | Town |
| Columbia | 13 | 669 | 662 | 0.15% | 11 | 61 | Town |
| Stratford | 14 | 643 | 661 | -0.62% | 8 | 79 | Town |
| Stark | 15 | 461 | 475 | -0.65% | 8 | 59 | Town |
| Shelburne | 16 | 362 | 354 | 0.28% | 8 | 48 | Town |
| Randolph | 17 | 327 | 329 | 0% | 7 | 47 | Town |
| Dummer | 18 | 315 | 305 | 0.32% | 7 | 48 | Town |
| Errol | 19 | 289 | 299 | -0.69% | 5 | 60 | Town |
| Clarksville | 20 | 281 | 290 | -0.71% | 5 | 60 | Town |
Berlin is the largest city in Coos County, with a population of 9,136.
Clarksville is the smallest city in Coos County, with a population of 281.
There are 20 cities in Coos County, New Hampshire.