| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density (/mi²) | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Concord | 1 | 44,621 | 44,047 | 0.05% | 698 | 64 | City |
| Hooksett | 2 | 15,372 | 14,912 | 0.17% | 426 | 36 | Town |
| Franklin | 3 | 8,865 | 8,747 | 0.29% | 323 | 27 | City |
| Bow | 4 | 8,453 | 8,247 | 0.45% | 300 | 28 | Town |
| Pembroke | 5 | 7,634 | 7,204 | 0.73% | 337 | 23 | Town |
| Henniker | 6 | 6,284 | 6,201 | 0.45% | 142 | 44 | Town |
| Hopkinton | 7 | 6,122 | 5,924 | 0.03% | 141 | 43 | Town |
| Loudon | 8 | 5,813 | 5,600 | 0.55% | 126 | 46 | Town |
| Northfield | 9 | 5,105 | 4,875 | 0.47% | 179 | 29 | Town |
| Epsom | 10 | 5,094 | 4,841 | 0.73% | 148 | 34 | Town |
| Allenstown | 11 | 4,900 | 4,715 | 0.37% | 239 | 20 | Town |
| New London | 12 | 4,406 | 4,412 | -0.11% | 197 | 22 | Town |
| Boscawen | 13 | 4,295 | 4,005 | 0.94% | 173 | 25 | Town |
| Pittsfield | 14 | 4,159 | 4,079 | 0.27% | 173 | 24 | Town |
| Dunbarton | 15 | 3,286 | 3,012 | 1.64% | 106 | 31 | Town |
| Warner | 16 | 2,911 | 2,932 | 0.31% | 53 | 55 | Town |
| Chichester | 17 | 2,856 | 2,670 | 0.78% | 135 | 21 | Town |
| Andover | 18 | 2,468 | 2,403 | 0.49% | 61 | 40 | Town |
| Canterbury | 19 | 2,467 | 2,388 | 0.16% | 56 | 44 | Town |
| Newbury | 20 | 2,337 | 2,177 | 1.08% | 65 | 36 | Town |
| Sutton | 21 | 2,067 | 1,985 | 0.15% | 49 | 43 | Town |
| Webster | 22 | 1,976 | 1,920 | 0.2% | 70 | 28 | Town |
| Bradford | 23 | 1,728 | 1,660 | 0.29% | 49 | 35 | Town |
| Salisbury | 24 | 1,528 | 1,428 | 0.79% | 39 | 40 | Town |
| Wilmot | 25 | 1,475 | 1,409 | 0.27% | 50 | 29 | Town |
| Danbury | 26 | 1,335 | 1,255 | 1.37% | 35 | 38 | Town |
| Hill | 27 | 1,052 | 1,013 | 0.38% | 40 | 27 | Town |
Concord is the largest city in Merrimack County, with a population of 44,621.
Hill is the smallest city in Merrimack County, with a population of 1,052.
There are 27 cities in Merrimack County, New Hampshire.