Portsmouth is the only city located in Rockingham County, New Hampshire. Despite being the only city in the county, it is actually the fourth-largest community in Rockingham County. Portsmouth was home to the Strategic Air Command's Pease Air Force Base, which is known today as as Portsmouth International Airport at Pease. As of the 2013 census, Portsmouth, NH has a population of over 21,400.
Although it was settled in 1623, Portsmouth was incorporated as a town in 1653. It received its name from John Mason, the colony's founder who was the captain of the port of Portsmouth, England. In 1849, Portsmouth, NH was officially incorporated as a city. Because of its location near the Piscataqua River, Portsmouth was once of the nation's busiest ports and shipbuilding cities.