Adjacent counties

• Carroll County (north)
• York County, Maine (east)
• Rockingham County (south)
• Merrimack County (west)
• Belknap County (northwest)

2000 census

As of the census^[10] of 2000, there were 112,233 people, 42,581 households, and 27,762 families living in the county. The population density was 304 inhabitants per square mile (117/km²). There were 45,539 housing units at an average density of 124 units per square mile (48/km²). 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. 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) .

2010 census

As of the 2010 United States Census, there were 123,143 people, 47,100 households, and 29,862 families living in the county.^[11] The population density was 333.7 inhabitants per square mile (128.8/km²). There were 51,697 housing units at an average density of 140.1 per square mile (54.1/km²).^[12] The racial makeup of the county was 93.8% white, 2.6% Asian, 1.0% black or African American, 0.2% American Indian, 0.5% from other races, and 1.9% from two or more races. Those of Hispanic or Latino origin made up 1.8% of the population.^[11] In terms of ancestry, 24.4% were French or French Canadian, 19.7% were Irish, 17.4% were English, 9.5% were Italian, 8.7% were German, 5.2% were American, and 5.0% were Scottish.^[13]

Of the 47,100 households, 30.6% had children under the age of 18 living with them, 48.4% were married couples living together, 10.5% had a female householder with no husband present, 36.6% were non-families, and 26.3% of all households were made up of individuals. The average household size was 2.44 and the average family size was 2.93. The median age was 36.9 years.^[11]

The median income for a household in the county was $57,809 and the median income for a family was $72,286. Males had a median income of $50,489 versus $37,178 for females. The per capita income for the county was $28,059. About 6.7% of families and 11.3% of the population were below the poverty line, including 12.3% of those under age 18 and 8.0% of those age 65 or over.^[14]

County Commission

The executive power of Strafford County's government is held by three county commissioners.^[16]

In addition to the County Commission, there are five directly elected officials: they include County Attorney, Register of Deeds, County Sheriff, Register of Probate, and County Treasurer.^[16]

General court

The general court delegation of Strafford County is made up of all of the members of the New Hampshire House of Representatives from the county. There are 37 members from 25 different districts. After the 2020 elections, the party distribution of representatives for the county was as follows.^[17]

Cities

• Dover (county seat)
• Rochester
• Somersworth

Towns

Census-designated places

• Durham
• Farmington
• Milton
• Milton Mills

Villages

• Bow Lake Village
• Center Strafford
• East Rochester
• Gonic
• North Rochester
• Place