RANKING · 2025 ESTIMATES · 10 SHOWN OF 10

Largest by population, New Hampshire counties

The most populous New Hampshire counties as of the 2025 population estimates. This list covers the 10 counties in New Hampshire that qualify, ranked against each other statewide.

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SAME RANKING BYCities States Metros ZIP codes

RELATEDFastest growing Fastest shrinking Most population gained Most population lost Most densely populated Most sparsely populated

YEAR1990 2000 2010 2020 2025

RANKPLACESTATETOTAL POPULATIONVS 2000

01Hillsborough County, NHNH433,415+14%

02Rockingham County, NHNH324,077+17%

03Merrimack County, NHNH158,078+16%

04Strafford County, NHNH135,043+20%

05Grafton County, NHNH93,225+14%

06Cheshire County, NHNH78,269+6%

07Belknap County, NHNH65,147+16%

08Carroll County, NHNH52,784+21%

09Sullivan County, NHNH43,961+9%

10Coos County, NHNH31,343−5%

SHOWING 1–10 OF 10

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UPDATED 2026-08-08 · DATA: US CENSUS BUREAU POPULATION ESTIMATES