Keystone is a census-designated place (CDP) in Summit County, Colorado, United States. The population was 1,079 at the 2010 census. The Dillon Post Office (ZIP Code 80435) serves Keystone postal addresses.
Keystone is located at 39°36′15″N 105°56′53″W / 39.604233°N 105.948111°W / 39.604233; -105.948111.
According to the United States Census Bureau, the CDP has a total area of 40.6 square miles (105 km), of which, 40.6 square miles (105 km) of it is land and 0.02% is water.
As of the census of 2000, there were 825 people, 327 households, and 88 families residing in the CDP. The population density was 20.3 people per square mile (7.8/km²). There were 2,606 housing units at an average density of 64.1 per square mile (24.8/km²). The racial makeup of the CDP was 86.55% White, 0.48% African American, 1.33% Asian, 9.09% from other races, and 2.55% from two or more races. Hispanic or Latino of any race were 13.58% of the population.
There were 327 households out of which 6.7% had children under the age of 18 living with them, 22.0% were married couples living together, 1.5% had a female householder with no husband present, and 72.8% were non-families. 21.1% of all households were made up of individuals and 0.6% had someone living alone who was 65 years of age or older. The average household size was 2.23 and the average family size was 2.42.
In the CDP, the population was spread out with 7.2% under the age of 18, 39.9% from 18 to 24, 36.5% from 25 to 44, 12.5% from 45 to 64, and 4.0% who were 65 years of age or older. The median age was 26 years. For every 100 females, there were 186.5 males. For every 100 females age 18 and over, there were 195.8 males.
The median income for a household in the CDP was $43,654, and the median income for a family was $68,750. Males had a median income of $26,563 versus $30,833 for females. The per capita income for the CDP was $24,085. None of the families and 22.1% of the population were living below the poverty line, including no under eighteens and none of those over 64.