Greenfield is a town in Hillsborough County, New Hampshire, United States. The population was 1,749 at the 2010 census. Greenfield is home to the Crotched Mountain Rehabilitation Center, to Greenfield State Park, and to part of the Wapack Trail.
According to the United States Census Bureau, the town has a total area of 26.6 square miles (68.9 km), of which 26.1 square miles (67.6 km) is land and 0.5 square miles (1.3 km) is water, comprising 2.09% of the town. Greenfield is drained by Stony Brook, Otter Brook and the Contoocook River; the town lies fully within the Merrimack River watershed. North Pack Monadnock Mountain, elevation 2,276 feet (694 m) above sea level, is the northernmost summit of the Wapack Range and the highest point in Greenfield.
As of the census of 2000, there were 1,657 people, 563 households, and 405 families residing in the town. The population density was 65.1 people per square mile (25.1/km²). There were 640 housing units at an average density of 25.1 per square mile (9.7/km²). The racial makeup of the town was 97.28% White, 0.72% African American, 0.84% Native American, 0.24% Asian, 0.48% from other races, and 0.42% from two or more races. Hispanic or Latino of any race were 0.60% of the population.
There were 563 households out of which 38.9% had children under the age of 18 living with them, 60.0% were married couples living together, 8.0% had a female householder with no husband present, and 27.9% were non-families. 19.5% of all households were made up of individuals and 4.3% had someone living alone who was 65 years of age or older. The average household size was 2.69 and the average family size was 3.12.
In the town, the population was spread out with 30.8% under the age of 18, 7.3% from 18 to 24, 32.1% from 25 to 44, 22.8% from 45 to 64, and 7.1% who were 65 years of age or older. The median age was 34 years. For every 100 females, there were 104.1 males. For every 100 females age 18 and over, there were 105.9 males.
The median income for a household in the town was $48,833, and the median income for a family was $56,250. Males had a median income of $36,250 versus $24,438 for females. The per capita income for the town was $19,895. About 2.4% of families and 5.4% of the population were below the poverty line, including 6.9% of those under age 18 and 8.5% of those age 65 or over.