Rockingham County, New Hampshire

Rockingham County
County
Aerial view of Portsmouth
Flag Seal
Location within the U.S. state of New Hampshire
New Hampshire's location within the U.S.
Coordinates: 42°57′46″N 71°04′39″W / 42.962872°N 71.077621°W / 42.962872; -71.077621
Country	United States
State	New Hampshire
Founded	1769
Named for	Charles Watson-Wentworth, 2nd Marquess of Rockingham
Seat	Brentwood
Largest town	Derry
Area
• Total	795.2 sq mi (2,060 km2)
• Land	695.4 sq mi (1,801 km2)
• Water	99.9 sq mi (259 km2)  12.6%
Population  (2020)
• Total	314,176
• Estimate  (2022)	319,424
• Density	400/sq mi (150/km2)
Time zone	UTC−5 (Eastern)
• Summer (DST)	UTC−4 (EDT)
Congressional districts	1st, 2nd
Website	www.rockinghamcountynh.org

Rockingham County is a county in the U.S. state of New Hampshire. As of the 2020 census, the population was 314,176,^[1] making it New Hampshire's second-most populous county. The county seat is Brentwood.^[2] Rockingham County is part of the Boston-Cambridge-Newton, MA-NH Metropolitan Statistical Area and the greater Boston-Worcester-Providence, MA-RI-NH-CT Combined Statistical Area. Per the 2020 census, it was New Hampshire's fastest growing county from 2010 to 2020.^[3]

As of 2014–2018 estimates from the American Community Survey, Rockingham County was the fourth- wealthiest county in New England, with a median household income of $90,429.^[4]