The
United States Census Bureau initially defined the for the
2020 census As of the
2020 census, Holly Hills had a population of 2,683. The median age was 44.3 years. 20.6% of residents were under the age of 18 and 23.1% of residents were 65 years of age or older. For every 100 females there were 97.9 males, and for every 100 females age 18 and over there were 93.3 males age 18 and over. 100.0% of residents lived in urban areas, while 0.0% lived in rural areas. There were 1,030 households in Holly Hills, of which 32.7% had children under the age of 18 living in them. Of all households, 56.7% were married-couple households, 14.3% were households with a male householder and no spouse or partner present, and 23.6% were households with a female householder and no spouse or partner present. About 22.6% of all households were made up of individuals and 11.3% had someone living alone who was 65 years of age or older. There were 1,056 housing units, of which 2.5% were vacant. The homeowner vacancy rate was 1.0% and the rental vacancy rate was 7.1%. ==Education==