Summerhill is a town in Cayuga County, New York, United States. The population was 1,217 at the 2010 census. The town name is that of a location in Ireland. Summerhill is in the southeast corner of the county and is northeast of Ithaca.
According to the United States Census Bureau, the town has a total area of 26.0 square miles (67.3 km), of which 25.9 square miles (67.0 km) is land and 0.12 square miles (0.3 km), or 0.47%, is water.
The south town line is the border of Tompkins County, and the east town line is the border of Cortland County.
New York State Route 90 is an east-west highway in south of Summerhill. New York State Route 41A crosses the northeast part of the town.
As of the census of 2000, there were 1,098 people, 393 households, and 304 families residing in the town. The population density was 42.4 people per square mile (16.4/km²). There were 463 housing units at an average density of 17.9 per square mile (6.9/km²). The racial makeup of the town was 99.27% White, 0.18% African American, 0.18% Native American, and 0.36% from two or more races. Hispanic or Latino of any race were 0.64% of the population.
There were 393 households out of which 37.4% had children under the age of 18 living with them, 60.3% were married couples living together, 7.9% had a female householder with no husband present, and 22.6% were non-families. 16.0% of all households were made up of individuals and 6.1% 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 3.06.
In the town, the population was spread out with 29.2% under the age of 18, 7.6% from 18 to 24, 30.1% from 25 to 44, 23.8% from 45 to 64, and 9.3% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 105.2 males. For every 100 females age 18 and over, there were 105.0 males.
The median income for a household in the town was $39,000, and the median income for a family was $39,500. Males had a median income of $26,336 versus $24,375 for females. The per capita income for the town was $14,609. About 6.9% of families and 12.1% of the population were below the poverty line, including 21.8% of those under age 18 and 2.0% of those age 65 or over.