Carroll County is part of the Lafayette, Indiana Metropolitan Statistical Area.
2000 20,165 1990 18,809 1980 19,722 1970 17,734 1960 16,934 1950 16,010 1940 15,410 1930 15,049 1920 16,315 1910 17,970 1900 19,953 1890 20,021 1880 18,345 1870 16,152 1860 13,489 1850 11,015 1840 7,819 1830 1,611
As of the census of 2000, there were 20,165 people, 7,718 households, and 5,688 families residing in the county. The population density was 54 people per square mile (21/km²). There were 8,675 housing units at an average density of 23 per square mile (9/km²). The racial makeup of the county was 97.65% White, 0.20% Black or African American, 0.16% Native American, 0.06% Asian, 1.39% from other races, and 0.54% from two or more races. 2.93% of the population were Hispanic or Latino of any race. 28.8% were of American, 25.1% German, 9.8% Irish and 8.8% English ancestry according to Census 2000.
There were 7,718 households out of which 33.20% had children under the age of 18 living with them, 63.50% were married couples living together, 6.50% had a female householder with no husband present, and 26.30% were non-families. 22.80% of all households were made up of individuals and 10.50% had someone living alone who was 65 years of age or older. The average household size was 2.59 and the average family size was 3.04.
In the county the population was spread out with 26.30% under the age of 18, 7.40% from 18 to 24, 28.70% from 25 to 44, 23.60% from 45 to 64, and 13.90% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 99.60 males. For every 100 females age 18 and over, there were 96.80 males.
The median income for a household in the county was $42,677, and the median income for a family was $50,216. Males had a median income of $35,348 versus $21,385 for females. The per capita income for the county was $19,436. About 4.30% of families and 6.80% of the population were below the poverty line, including 9.00% of those under age 18 and 6.30% of those age 65 or over.