Strafford County is a county located in the U.S. state of New Hampshire. As of 2010, the population was 123,143. Its county seat is Dover.
Strafford County was one of the five original counties identified for New Hampshire in 1769. It was named for William Wentworth, 2nd Earl of Strafford in the mistaken belief that he was the ancestor of governor John Wentworth. Although they were distantly related, William had no descendants. The county was organized at Dover in 1771. In 1840 the original size of the county was reduced with the creation of Belknap County.
Strafford County is the smallest county in area in New Hampshire. According to the U.S. Census Bureau, the county has a total area of 384 square miles, of which 369 sq mi is land and 15 sq mi (3.95%) is water.
As of the census of 2000, there were 112,233 people, 42,581 households, and 27,762 families residing in the county. The population density was 304 people per square mile. There were 45,539 housing units at an average density of 124 per square mile. The racial makeup of the county was 96.29% White, 0.63% Black or African American, 0.21% Native American, 1.39% Asian, 0.05% Pacific Islander, 0.30% from other races, and 1.14% from two or more races. 1.03% of the population were Hispanic or Latino of any race. 15.8% were of English, 14.9% Irish, 14.0% French, 10.5% French Canadian, 7.6% American, 6.3% Italian and 6.2% German ancestry according to Census 2000. 93.7% spoke English and 3.2% French as their first language.
There were 42,581 households out of which 32.60% had children under the age of 18 living with them, 51.10% were married couples living together, 10.00% had a female householder with no husband present, and 34.80% were non-families. 24.80% of all households were made up of individuals and 8.20% had someone living alone who was 65 years of age or older. The average household size was 2.50 and the average family size was 2.98.
In the county the population was spread out with 23.70% under the age of 18, 13.60% from 18 to 24, 30.60% from 25 to 44, 20.90% from 45 to 64, and 11.20% who were 65 years of age or older. The median age was 34 years. For every 100 females there were 94.30 males. For every 100 females age 18 and over, there were 91.10 males.
The median income for a household in the county was $44,803, and the median income for a family was $53,075. Males had a median income of $36,661 versus $26,208 for females. The per capita income for the county was $20,479. About 5.00% of families and 9.20% of the population were below the poverty line, including 9.10% of those under age 18 and 6.60% of those age 65 or over.
The largest cities in Strafford County are Dover (population) and Rochester (land area) .