What are the fastest-growing counties in New Hampshire?
Carroll County is the fastest-growing county in New Hampshire: its population grew 0.99% a year from 2020 to 2025, to 52,784 residents (Census PEP Vintage 2025). Strafford County (0.60%) and Rockingham County (0.59%) follow. New Hampshire as a whole grew 0.53% a year to 1,415,342 residents.
Data as of 2026-09-23. Population, growth and migration: PEP Vintage 2025 · 2020–2025. Income migration: IRS SOI 2022–2023 (2-yr lag).
Top 10 counties in New Hampshire by population growth, 2020 to 2025
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Carroll County | 52,784 | 0.99% | +4,200 | +76 | +$109.2M |
| 2 | Strafford County | 135,043 | 0.60% | +3,878 | +754 | -$28.5M |
| 3 | Rockingham County | 324,077 | 0.59% | +9,215 | +1,273 | +$342.7M |
| 4 | Merrimack County | 158,078 | 0.52% | +4,835 | +744 | +$59.9M |
| 5 | Hillsborough County | 433,415 | 0.49% | +892 | +8,142 | -$10.5M |
| 6 | Cheshire County | 78,269 | 0.45% | +2,478 | +249 | +$30.6M |
| 7 | Grafton County | 93,225 | 0.44% | +2,740 | +788 | +$76.4M |
| 8 | Belknap County | 65,147 | 0.43% | +3,374 | -9 | +$131.3M |
| 9 | Sullivan County | 43,961 | 0.41% | +1,681 | +120 | +$27.8M |
| 10 | Coos County | 31,343 | 0.07% | +1,669 | +78 | +$17.4M |
Where are people moving in New Hampshire?
Rockingham County gained the most people from elsewhere in the United States: net domestic migration of +9,215 from 2020 to 2025 (Census PEP Vintage 2025). The table ranks every New Hampshire place with 10,000 or more residents by that figure; the IRS column shows net adjusted gross income migration for 2022 to 2023.
| Rank | County | Population | Growth (% per year) | Net domestic migration | Net international migration | IRS net AGI migration |
|---|---|---|---|---|---|---|
| 1 | Rockingham County | 324,077 | 0.59% | +9,215 | +1,273 | +$342.7M |
| 2 | Merrimack County | 158,078 | 0.52% | +4,835 | +744 | +$59.9M |
| 3 | Carroll County | 52,784 | 0.99% | +4,200 | +76 | +$109.2M |
| 4 | Strafford County | 135,043 | 0.60% | +3,878 | +754 | -$28.5M |
| 5 | Belknap County | 65,147 | 0.43% | +3,374 | -9 | +$131.3M |
| 6 | Grafton County | 93,225 | 0.44% | +2,740 | +788 | +$76.4M |
| 7 | Cheshire County | 78,269 | 0.45% | +2,478 | +249 | +$30.6M |
| 8 | Sullivan County | 43,961 | 0.41% | +1,681 | +120 | +$27.8M |
| 9 | Coos County | 31,343 | 0.07% | +1,669 | +78 | +$17.4M |
| 10 | Hillsborough County | 433,415 | 0.49% | +892 | +8,142 | -$10.5M |
Go past the headline numbers
The interactive Demographics map layer and the full report for a single place are part of paid plans.
Get the Demographics Report for Carroll CountyFrequently asked questions
- What are the fastest-growing counties in New Hampshire?
- By population growth from 2020 to 2025, the fastest are Carroll County (0.99% a year), Strafford County (0.60% a year), Rockingham County (0.59% a year), Merrimack County (0.52% a year) and Hillsborough County (0.49% a year) (Census PEP Vintage 2025). Only places with 10,000 or more residents are ranked.
- Where are people moving in New Hampshire?
- By net domestic migration from 2020 to 2025, the largest gains are Rockingham County (+9,215), Merrimack County (+4,835) and Carroll County (+4,200) (Census PEP Vintage 2025).
- How fast is New Hampshire growing overall?
- New Hampshire grew 0.53% a year from 2020 to 2025, to 1,415,342 residents, with net migration of +47,177 people (Census PEP Vintage 2025).
- Where does this New Hampshire data come from, and how current is it?
- Population, growth and migration come from the U.S. Census Bureau Population Estimates Program (PEP Vintage 2025 · 2020–2025). Income migration comes from IRS Statistics of Income (IRS SOI 2022–2023 (2-yr lag)). Counties with fewer than 10,000 residents are not ranked. Data last loaded 2026-09-23.
Data as of 2026-09-23: sources and periods
- Population, growth and migration
- U.S. Census Bureau, Population Estimates Program: PEP Vintage 2025 · 2020–2025. census.gov/programs-surveys/popest
- Income migration (net AGI)
- Internal Revenue Service, Statistics of Income migration data: IRS SOI 2022–2023 (2-yr lag). irs.gov/statistics/soi-tax-stats-migration-data
How to read the table
- Population is the Census July 1 estimate of the latest vintage.
- Growth is the compound annual rate over 2020 to 2025.
- Net domestic and international migration are cumulative people over 2020 to 2025.
- IRS net AGI migration is adjusted gross income that moved in, less what moved out, for 2022 to 2023. A plus sign means a net inflow.
- Places with fewer than 10,000 residents are left out of the rankings.