Merrimack County, New Hampshire

Merrimack County
Merrimack County Courthouse, 2019
Location within the U.S. state of New Hampshire
New Hampshire's location within the U.S.
Coordinates: 43°18′N 71°41′W / 43.3°N 71.68°W / 43.3; -71.68
Country United States
State New Hampshire
Founded1823
Named afterMerrimack River
SeatConcord
Largest cityConcord
Area
  Total
955.0 sq mi (2,473 km2)
  Land932.9 sq mi (2,416 km2)
  Water22.1 sq mi (57 km2)  2.3%
Population
 (2020)
  Total
153,808
  Estimate 
(2022)
156,020
  Density167.2/sq mi (64.6/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional districts1st, 2nd
Websitewww.merrimackcounty.net

Merrimack County is a county in the U.S. state of New Hampshire. As of the 2020 Census, the population was 153,808, making it the third most populous county in New Hampshire. Its county seat is Concord, the state capital. The county was organized in 1823 from parts of Hillsborough and Rockingham counties, and is named for the Merrimack River. Merrimack County comprises the Concord, NH Micropolitan Statistical Area, which in turn constitutes a portion of the BostonWorcesterProvidence, MARINHCT Combined Statistical Area. In 2010, the center of population of New Hampshire was located in Merrimack County, in the town of Pembroke.