The Town of Harpersfield is on the northern border of the county.
According to the United States Census Bureau, the town has a total area of 42.4 square miles (109.7 km²), of which, 42.1 square miles (109.1 km²) of it is land and 0.2 square miles (0.5 km²) of it (0.50%) is water.
There were 591 households out of which 26.6% had children under the age of 18 living with them, 58.0% were married couples living together, 8.3% had a female householder with no husband present, and 29.6% were non-families. 23.9% of all households were made up of individuals and 11.3% had someone living alone who was 65 years of age or older. The average household size was 2.48 and the average family size was 2.92.
In the town the population was spread out with 21.5% under the age of 18, 6.6% from 18 to 24, 20.4% from 25 to 44, 26.6% from 45 to 64, and 25.0% who were 65 years of age or older. The median age was 46 years. For every 100 females there were 90.6 males. For every 100 females age 18 and over, there were 89.0 males.
The median income for a household in the town was $33,333, and the median income for a family was $37,446. Males had a median income of $27,237 versus $21,500 for females. The per capita income for the town was $18,863. About 12.5% of families and 18.3% of the population were below the poverty line, including 38.0% of those under age 18 and 7.4% of those age 65 or over.