17 cities
| City | Rank | 2026 Pop. ↓ | 2020 Pop. | Annual Change | Density | Area (mi²) | Type |
|---|---|---|---|---|---|---|---|
| Dover | 1 | 34,721 | 32,783 | 1.18% | 1,299 | 27 | City |
| Dover | 2 | 34,472 | 32,783 | 0.82% | 1,290 | 27 | City |
| Rochester | 3 | 34,136 | 32,521 | 0.79% | 758 | 45 | City |
| Rochester | 4 | 33,748 | 32,521 | 0.22% | 750 | 45 | City |
| Durham | 5 | 15,228 | 15,557 | -0.14% | 679 | 22 | Town |
| Somersworth | 6 | 12,364 | 11,925 | 0.59% | 1,262 | 10 | City |
| Somersworth | 7 | 12,276 | 11,925 | 0.24% | 1,253 | 10 | City |
| Barrington | 8 | 9,779 | 9,320 | 0.77% | 210 | 47 | Town |
| Farmington | 9 | 6,762 | 6,708 | -0.32% | 185 | 37 | Town |
| Milton | 10 | 4,588 | 4,474 | 0.17% | 139 | 33 | Town |
| Lee | 11 | 4,576 | 4,525 | -0.11% | 229 | 20 | Town |
| Strafford | 12 | 4,347 | 4,236 | 0.09% | 89 | 49 | Town |
| New Durham | 13 | 2,870 | 2,699 | 0.99% | 70 | 41 | Town |
| Rollinsford | 14 | 2,687 | 2,592 | 0.52% | 369 | 7 | Town |
| Madbury | 15 | 1,939 | 1,911 | -0.15% | 167 | 12 | Town |
| Middleton | 16 | 1,869 | 1,823 | 0.32% | 103 | 18 | Town |
| Newington | 17 | 859 | 816 | 1.3% | 106 | 8 | Town |
Dover is the largest city in Strafford County, with a population of 34,721.
Newington is the smallest city in Strafford County, with a population of 859.
There are 17 cities in Strafford County, New Hampshire.