RANKING · 2025 ESTIMATES · 10 SHOWN OF 10

Most population gained, New Hampshire counties

New Hampshire counties that added the most residents from the 2020 census to 2025, by raw count of people rather than percentage. 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

YEAR2000 2010 2020 2025

RANKPLACESTATEPOPPOPULATION CHANGEVS 2000

01Hillsborough County, NHNH433,415+10,478−77%

02Rockingham County, NHNH324,077+9,901−69%

03Merrimack County, NHNH158,078+4,270−74%

04Strafford County, NHNH135,043+4,154−48%

05Carroll County, NHNH52,784+2,677−68%

06Grafton County, NHNH93,225+2,107−69%

07Cheshire County, NHNH78,269+1,811−51%

08Belknap County, NHNH65,147+1,442−80%

09Sullivan County, NHNH43,961+898−52%

10Coos County, NHNH31,343+75−104%

SHOWING 1–10 OF 10

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UPDATED 2026-07-15 · DATA: US CENSUS BUREAU POPULATION ESTIMATES