Census ACS · 10 counties
Largest Counties in New Hampshire
New Hampshire has 10 counties with Census data available. The largest is Hillsborough County with a population of 424,732. County-level data is important because counties are the primary unit of local government in most states, responsible for courts, elections, public health, and infrastructure. Population distribution across counties reveals where growth is concentrated and where rural decline may be occurring.
Source: Census ACS 5-Year Estimates
| # | County | Population | Median Income |
|---|---|---|---|
| 1 | Sullivan County | 43,529 | $75,929 |
| 2 | Strafford County | 131,743 | $86,564 |
| 3 | Rockingham County | 317,163 | $113,927 |
| 4 | Merrimack County | 155,018 | $93,944 |
| 5 | Hillsborough County | 424,732 | $100,436 |
| 6 | Grafton County | 91,759 | $84,021 |
| 7 | Coos County | 31,386 | $58,439 |
| 8 | Cheshire County | 76,945 | $81,001 |
| 9 | Carroll County | 51,259 | $82,961 |
| 10 | Belknap County | 64,300 | $87,983 |
More Rankings for New Hampshire
Frequently Asked Questions
Hillsborough County is the #1 ranked county in New Hampshire by population, with a value of 424,732 according to latest Census ACS data.
New Hampshire has 10 counties tracked in latest Census ACS data.
All data comes from the American Community Survey (ACS) 5-Year estimates by the US Census Bureau.
Data from the American Community Survey 5-Year estimates. Covers all counties in New Hampshire.
Source: U.S. Census Bureau ACS, 2026.