Keystone is located in Pennington county South dakota with a geographic area of 3.0 square miles. The total population in Keystone is 542 with 55.0% male and 45.0% female. Children under age 5 represent 5.2% of the population, under age 18 equal 27.1% of the population and over age 65 is 10.3% of the population. The median household income is $51,719, per capita income is $24,018. There are a total of 161 housing units with 57.8% owner occupied. Education includes 34.8% of residents that are high school graduates and 18.0% with a bachelor's degree or higher. The average temperature in Keystone in the summer is 70 degrees, and in the winter 15 degrees.
