| County | Rank | Change (2020) ↓ | 2026 Pop. | 2020 Pop. |
|---|---|---|---|---|
| Carroll County | 1 | 5.48% | 52,994 | 50,240 |
| Rockingham County | 2 | 3.59% | 325,969 | 314,664 |
| Merrimack County | 3 | 3.54% | 159,489 | 154,039 |
| Strafford County | 4 | 3.29% | 135,390 | 131,074 |
| Cheshire County | 5 | 3.17% | 78,970 | 76,542 |
| Hillsborough County | 6 | 3.08% | 435,948 | 422,929 |
| Belknap County | 7 | 3.07% | 65,733 | 63,774 |
| Grafton County | 8 | 2.32% | 93,317 | 91,197 |
| Sullivan County | 9 | 2.22% | 44,024 | 43,069 |
| Coos County | 10 | -1.17% | 30,864 | 31,228 |
New Hampshire's counties show varied growth patterns from 2020 to 2026. Carroll County leads with 0.89% annualized growth, followed by Rockingham County (0.59%) and Merrimack County (0.58%). The largest counties are Hillsborough County (435,948), Rockingham County (325,969), and Merrimack County (159,489). Of the 10 counties in New Hampshire, 9 are growing while 1 has experienced population decline. Overall, counties averaged 0.47% annualized growth, with total population growing by 0.52% annually.
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