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2020 census As of the
2020 census, Keystone had a population of 25,211. The median age was 44.8 years. 24.7% of residents were under the age of 18 and 16.3% of residents were 65 years of age or older. For every 100 females there were 97.4 males, and for every 100 females age 18 and over there were 94.8 males age 18 and over. 86.9% of residents lived in urban areas, while 13.1% lived in rural areas. There were 8,699 households in Keystone, of which 40.9% had children under the age of 18 living in them. Of all households, 72.2% were married-couple households, 9.6% were households with a male householder and no spouse or partner present, and 14.2% were households with a female householder and no spouse or partner present. About 13.0% of all households were made up of individuals and 6.4% had someone living alone who was 65 years of age or older.). Males had a median income of $55,905 versus $37,190 for females. The
per capita income for the community was $35,136. About 1.4% of families and 2.4% of the population were below the
poverty line, including 2.7% of those under age 18 and 5.4% of those age 65 or over. ==Schools==