Seabrook is a town in Rockingham County, New Hampshire, United States. The population was 8,693 at the 2010 census. Located at the southern end of the coast of New Hampshire on the border with Massachusetts, Seabrook is noted as the location of the Seabrook Nuclear Power Station, the third-most recently constructed nuclear power plant in the United States.
According to the United States Census Bureau, the town has a total area of 9.6 square miles (25 km), of which 8.9 sq mi (23 km) is land and 0.8 sq mi (2.1 km) is water, comprising 7.8% of the town. The census-designated place of Seabrook Beach occupies the eastern end of the town, along the Atlantic Ocean. The highest point in Seabrook is 217 feet (66 m) above sea level on Grape Hill, whose 230-foot (70 m) summit lies just south of the town line in Salisbury, Massachusetts.
At the 2000 census, there were 7,979 people, 3,425 households and 2,161 families residing in the town. The population density was 895.0 per square mile (345.7/km²). There were 4,066 housing units at an average density of 458.7 per square mile (177.2/km²). The racial makeup of the town was 97.52% White, 0.34% African American, 0.24% Native American, 0.54% Asian, 0.38% from other races, and 0.98% from two or more races. Hispanic or Latino of any race were 0.86% of the population.
There were 3,425 households of which 24.3% had children under the age of 18 living with them, 48.2% were married couples living together, 10.2% had a female householder with no husband present, and 36.9% were non-families. 29.1% of all households were made up of individuals and 10.8% had someone living alone who was 65 years of age or older. The average household size was 2.32 and the average family size was 2.85.
Age distribution was 20.5% under the age of 18, 6.2% from 18 to 24, 30.4% from 25 to 44, 26.1% from 45 to 64, and 16.9% who were 65 years of age or older. The median age was 40 years. For every 100 females, there were 99.6 males. For every 100 females age 18 and over, there were 98.4 males.
The median household income was $42,874, and the median family income was $47,718. Males had a median income of $36,560 versus $27,143 for females. The per capita income for the town was $20,992. About 6.1% of families and 8.6% of the population were below the poverty line, including 15.9% of those under age 18 and 9.3% of those age 65 or over.