The area was first settled around 1785. The Town of Colesville was established in 1821 from part of the town of Windsor. Robert Harpur, an early developer, has lent his name to the community of Harpursville. He is believed to be responsible for the many classical names assigned to communities in central New York.
As of the census of 2000, there were 5,441 people, 1,944 households, and 1,458 families residing in the town. The population density was 69.3 people per square mile. There were 2,189 housing units at an average density of 27.9 per square mile. The racial makeup of the town was 97.85% White, 0.29% African American, 0.31% Native American, 0.35% Asian, 0.06% Pacific Islander, 0.02% from other races, and 1.12% from two or more races. Hispanic or Latino of any race were 0.74% of the population. There were 1,944 households, out of which 36.3% had children under the age of 18 living with them, 58.4% were married couples living together, 10.8% had a female householder with no husband present, and 25.0% were non-families. 19.2% of all households were made up of individuals, and 6.8% had someone living alone who was 65 years of age or older. The average household size was 2.79 and the average family size was 3.11. In the town, the population was spread out, with 29.4% under the age of 18, 6.5% from 18 to 24, 28.7% from 25 to 44, 23.9% from 45 to 64, and 11.4% who were 65 years of age or older. The median age was 37 years. For every 100 females, there were 100.0 males. For every 100 females age 18 and over, there were 98.6 males. The median income for a household in the town was $38,444, and the median income for a family was $40,333. Males had a median income of $31,462 versus $22,917 for females. The per capita income for the town was $15,816. About 6.7% of families and 10.3% of the population were below the poverty line, including 11.8% of those under age 18 and 9.5% of those age 65 or over.
Nathaniel Cole Park Pond - A lake located by West Colesville.
New Ohio - A hamlet in the northwest part of the town.
Nineveh - A hamlet northeast of Harpursville and on the north town line.
North Colesville - A hamlet in the northwest part of the town on NY-79.
Ouaquaga - A hamlet in the south part of the town.
Sanitaria Springs - A hamlet at the west town line, northwest of West Colesville on County Route 217; served by Exit 4 of Interstate 88. It was formerly called "Osborne Hollow."
Tunnel - A location south of New Ohio.
West Colesville - A hamlet on the south town line.
