Portsmouth was named one of the 2008 Dozen Distinctive Destinations by The National Trust for Historic Preservation.
The first known European to explore and write about the area was Martin Pring in 1603. It would be settled in 1630 as Piscataqua, then given the name Strawbery Banke because of abundant wild strawberries growing beside the Piscataqua River, a tidal estuary with a swift current. Strategically located for trade between various upstream industries (particularly logging) and mercantile interests abroad, the port prospered. Fishing, lumber and shipbuilding were principal businesses.
At the town's incorporation in 1653, the name Portsmouth was adopted in honor of the colony's founder, John Mason. He had been captain of the port of Portsmouth, England, in the county of Hampshire, for which New Hampshire is named. In 1679, Portsmouth became the colonial capital. It also became a refuge for exiles from Puritan Massachusetts. When Queen Anne's War ended, the town was selected by Governor Joseph Dudley to host the 1713 Treaty of Portsmouth, which ended hostilities between Eastern Abenaki Indians and English settlements of the Province of Massachusetts Bay and New Hampshire.
During the Revolution, in 1774 Paul Revere rode to Portsmouth warning that the British were coming. Although the harbor was protected by Fort William and Mary, the rebel government moved the capital inland to Exeter, particularly after Falmouth (now Portland, Maine) was bombarded by the Royal Navy on October 18, 1775. During President Thomas Jefferson's 1807 embargo, which withered trade, a number of local fortunes were lost. Others were gained by privateering during the War of 1812. In 1849, Portsmouth incorporated as a city.
Once one of the nation's busiest ports and shipbuilding cities, Portsmouth's wealth was expressed in fine architecture. It contains significant examples of Colonial, Georgian, and Federal style houses, a selection of which are now museums. Portsmouth's heart contains stately brick Federalist stores and townhouses, built all-of-a-piece after devastating early 19th century fires, the worst being in 1813 when 244 buildings burned. A fire district was subsequently created which required that all new buildings within the district be constructed of brick with slate roofs. The city is also noted for producing boldly veneered Federalist furniture, particularly that by master cabinet maker Langley Boardman.
The Industrial Revolution, however, would leave Portsmouth in the shadow of New Hampshire mill towns like Dover, Keene, Laconia, Manchester, Nashua and Rochester. The effect of this economic shift was to preserve old Portsmouth throughout its Victorian doldrums, a time described in the works of native son Thomas Bailey Aldrich. Now, with the protection of a Historic District Commission, much of the city's architectural legacy survives -- to the delight of tourists and artists, who each summer throng the cafes around Market Square.
Portsmouth shipbuilding history has a long symbiotic relationship with Kittery, Maine, across the Piscataqua River. Although John Paul Jones boarded at the Portsmouth house which now bears his name, his ship Ranger was built on Badger's Island in Kittery. The Portsmouth Naval Shipyard, established in 1800 as the first federal navy yard, is located on Seavey's Island in Kittery. President Theodore Roosevelt arranged for the base to host negotiations leading to the 1905 Treaty of Portsmouth, ending the Russo-Japanese War.
According to the United States Census Bureau, the city has a total area of , of which is land and is water, comprising 7.03% of the town. Portsmouth is drained by Sagamore Creek and the Piscataqua River. The highest point in the city is above sea level, within Pease International Airport.
As of the census of 2000, there were 20,784 people, 9,875 households, and 4,858 families residing in the city. The population density was 1,331.3 people per square mile (514.1/km²). There were 10,186 housing units at an average density of 652.5/sq mi (251.9/km²). The racial makeup of the city was 93.55% White, 2.13% African American, 0.21% Native American, 2.44% Asian, 0.02% Pacific Islander, 0.28% from other races, and 1.36% from two or more races. Hispanic or Latino of any race were 1.35% of the population.
There were 9,875 households out of which 20.0% had children under the age of 18 living with them, 37.8% were married couples living together, 8.6% had a female householder with no husband present, and 50.8% were non-families. 38.9% of all households were made up of individuals and 11.5% had someone living alone who was 65 years of age or older. The average household size was 2.04 and the average family size was 2.75.
In the city the population was spread out with 17.2% under the age of 18, 7.2% from 18 to 24, 36.2% from 25 to 44, 23.2% from 45 to 64, and 16.3% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 94.5 males. For every 100 females age 18 and over, there were 92.0 males.
The median income for a household in the city was $45,195, and the median income for a family was $59,630. Males had a median income of $41,966 versus $29,024 for females. The per capita income for the city was $27,540. About 6.4% of families and 9.3% of the population were below the poverty line, including 14.3% of those under age 18 and 8.4% of those age 65 or over.