2020 census
As of the 2020 census, Carroll Valley had a population of 3,940. The median age was 45.6 years. 19.9% of residents were under the age of 18 and 18.4% of residents were 65 years of age or older. For every 100 females there were 96.0 males, and for every 100 females age 18 and over there were 94.5 males age 18 and over.
0.0% of residents lived in urban areas, while 100.0% lived in rural areas.
There were 1,509 households in Carroll Valley, of which 29.2% had children under the age of 18 living in them. Of all households, 63.4% were married-couple households, 12.5% were households with a male householder and no spouse or partner present, and 18.2% were households with a female householder and no spouse or partner present. About 18.7% of all households were made up of individuals and 10.2% had someone living alone who was 65 years of age or older.
There were 1,595 housing units, of which 5.4% were vacant. The homeowner vacancy rate was 1.0% and the rental vacancy rate was 3.2%.
2000 census
As of the census of 2000, there were 3,291 people, 1,176 households, and 952 families residing in the borough. The population density was 610.4 inhabitants per square mile (235.7/km2). There were 1,261 housing units at an average density of 233.9 per square mile (90.3/km2). The racial makeup of the borough was 96.81% White, 0.61% African American, 0.43% Native American, 0.40% Asian, 0.24% from other races, and 1.52% from two or more races. Hispanic or Latino of any race were 0.79% of the population.
There were 1,176 households, out of which 43.5% had children under the age of 18 living with them, 71.9% were married couples living together, 5.6% had a female householder with no husband present, and 19.0% were non-families. 14.0% of all households were made up of individuals, and 4.0% had someone living alone who was 65 years of age or older. The average household size was 2.80 and the average family size was 3.08.
In the borough, the population was spread out, with 29.7% under the age of 18, 4.9% from 18 to 24, 35.2% from 25 to 44, 21.6% from 45 to 64, and 8.7% who were 65 years of age or older. The median age was 35 years. For every 100 females there were 100.4 males. For every 100 females age 18 and over, there were 101.3 males.
The median income for a household in the borough was $54,659, and the median income for a family was $55,000. Males had a median income of $40,135 versus $27,090 for females. The per capita income for the borough was $21,286. About 1.7% of families and 2.2% of the population were below the poverty line, including 2.0% of those under age 18 and 2.5% of those age 65 or over.
