According to the United States Census Bureau, the town has a total area of 204.5 km² (79.0 mi²). 199.9 km² (77.2 mi²) of it is land and 4.6 km² (1.8 mi²) of it (2.25%) is water.
The east town line is the border of Herkimer County, and The north town line is the border of Lewis County. The Black River and Kayuta Lake define the west town line.
As of the census of 2000, there were 1,692 people, 736 households, and 479 families residing in the town. The population density was 8.5/km² (21.9/mi²). There were 2,027 housing units at an average density of 10.1/km² (26.3/mi²). The racial makeup of the town was 98.52% White, 0.35% African American, 0.30% Native American, 0.18% Asian, 0.06% from other races, and 0.59% from two or more races. Hispanic or Latino of any race were 0.06% of the population.
There were 736 households out of which 25.7% had children under the age of 18 living with them, 53.9% were married couples living together, 7.3% had a female householder with no husband present, and 34.8% were non-families. 30.7% of all households were made up of individuals and 12.9% had someone living alone who was 65 years of age or older. The average household size was 2.30 and the average family size was 2.84.
In the town the population was spread out with 22.5% under the age of 18, 4.6% from 18 to 24, 25.2% from 25 to 44, 30.2% from 45 to 64, and 17.6% who were 65 years of age or older. The median age was 43 years. For every 100 females there were 103.4 males. For every 100 females age 18 and over, there were 103.7 males.
The median income for a household in the town was $34,455, and the median income for a family was $39,352. Males had a median income of $30,119 versus $25,060 for females. The per capita income for the town was $18,494. About 7.1% of families and 8.9% of the population were below the poverty line, including 11.4% of those under age 18 and 9.8% of those age 65 or over.
Communities and Locations in Forestport