The area was first settled around 1791. The town of Triangle was formed from the town of Lisle in 1831. The area had previously been called the "Chenango Triangle". In 1871, the community of Whitney Point incorporated as a village within the town.
As of the census of 2000, there were 3,032 people, 1,131 households, and 809 families residing in the town. The population density was 79.6 people per square mile. There were 1,245 housing units at an average density of 32.7 per square mile. The racial makeup of the town was 97.76% White, 0.20% African American, 0.26% Native American, 0.33% Asian, 0.10% Pacific Islander, 0.26% from other races, and 1.09% from two or more races. Hispanic or Latino of any race were 0.86% of the population. There were 1,131 households out of which 39.6% had children under the age of 18 living with them, 56.2% were married couplesliving together, 10.4% had a female householder with no husband present, and 28.4% were non-families. 21.9% of all households were made up of individuals and 8.0% had someone living alone who was 65 years of age or older. The average household size was 2.68 and the average family size was 3.14. In the town, the population was spread out with 29.5% under the age of 18, 7.8% from 18 to 24, 28.2% from 25 to 44, 23.1% from 45 to 64, and 11.4% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 97.5 males. For every 100 females age 18 and over, there were 94.3 males. The median income for a household in the town was $35,982, and the median income for a family was $41,220. Males had a median income of $29,184 versus $24,792 for females. The per capita income for the town was $15,734. About 10.0% of families and 11.4% of the population were below the poverty line, including 15.3% of those under age 18 and 5.5% of those age 65 or over.
Communities and locations in Triangle
Barnes Corners - A location in the northeast part of the town, north of the hamlet of Triangle.
Clough Corners - A hamlet near the north town line on County Road 144.
Hazzard Corners - A location east of Clough Corners.
Page Brook - A stream flowing into Whitney Point Reservoir.
Penelope - A location on the north town line.
Triangle - The hamlet of Triangle is in the south part of the town on NY Route 206 at the junction of County Road 133.
Upper Lisle - A hamlet at the north end of the Whitney Point Reservoir on NY-26.
Whitney Point - The village of Whitney Point is in the southwest part of the town by I-81 and US-11.
Whitney Point Reservoir - An artificial lake on the west side of the town, formed on the Otselic River, a tributary of the Tioughnioga River.
