Hillsborough County is the most populouscounty in theU.S. state ofNew Hampshire. As of the2020 census, the population was 422,937,[1] almost one-third the population of the entire state. Itscounty seats areManchester andNashua, the state's two biggest cities. Hillsborough is northernNew England's most populous county as well as its most densely populated.
In 1823, twelve townships of Hillsborough Country – Andover, Boscawen, Bradford, Dunbarton, Fishersfield (now Newbury), Henniker, Hooksett, Hopkinton, New London, Salisbury, Sutton, and Warner – became part ofMerrimack County. Thetown of Merrimack along theMerrimack River in south-central Hillsborough County was not included in the newly formed county 9 miles (14 km) to the north. Hillsborough County's administrative functions were moved from Amherst to Milford in 1866, and then to the current seats of Manchester and Nashua in 1869.
According to theUnited States Census Bureau, the county has a total area of 892 square miles (2,310 km2), of which 876 square miles (2,270 km2) is land and 16 square miles (41 km2) (1.8%) is water.[3] The highest point in Hillsborough county isPack Monadnock Mountain at 2,290 feet (700 m).
2020 presidential election by voting ward in Hillsborough County
In the 2012 presidential election,Time had listed Hillsborough as one of five critical counties affecting the outcome in the swing state of New Hampshire. Obama ended up winning with a margin of 50%–49%.[4]
Despite its more urban nature, Hillsborough County has historically been a more Republican leaning part of the state. But in 2020,Joe Biden andJeanne Shaheen won Hillsborough County by a wider margin than they won statewide by.[5]Biden also received the highest percentage of the vote for a Democrat sinceLyndon Johnson's1964 landslide, largely driven due to large swings toDemocrats in the county's historicallyRepublican suburban communities.[6] In 2024, the county voted for Democratic nomineeKamala Harris, the first time it voted for a Democrat who lost the presidential election since 1968.
United States presidential election results for Hillsborough County, New Hampshire[7]
The executive power of Hillsborough County's government is held by three county commissioners, each representing one of the three commissioner districts within the county.
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.[8]
The legislative branch of Hillsborough County, also known as the County Convention or County Delegation, is made up of all of the members of theNew Hampshire House of Representatives from the county.[11][12] As of 2022, there are 123 members from 45 districts.
2020 American Community Survey Population Estimates, Race and Hispanic Origin[18]
Race
Percentage
White, not Hispanic or Latino
83%
Asian
6%
Hispanic or Latino
8%
Black or African American
3%
As of thecensus of 2020, there were 422,937 people residing in the county.[19] The population density was 482.8 inhabitants per square mile (186.4/km2).
The racial makeup of the county was 81.0% white, 4.8% Asian, 3.9% black or African American, 1.7% American Indian, 2.1% from other races, and 2.0% from two or more races. Those of Hispanic or Latino origin made up 8% of the population.[20]
For the period 2011–2015, 24.8% of the county's population hadFrench ancestry (including 9.9% of the total population withFrench Canadian ancestry), 20.9% hadIrish, 13.1% hadEnglish, 10.2% hadItalian, and 8.2% hadGerman ancestry.[21] For the same time period, the estimated median annual income for a household in the county was $71,244, and the median income for a family was $85,966. Male full-time workers had a median income of $60,349 versus $44,270 for females. The per capita income for the county was $35,242. About 5.8% of families and 8.8% of the population were below thepoverty line, including 11.7% of those under age 18 and 5.9% of those age 65 or over.[22]
