Carroll County was formed on January 15, 1851, from sections of Pottawattamie County. It was named afterCharles Carroll[4] ofCarrollton,Maryland, the only Roman Catholic and longest-living signer of the Declaration of Independence. In 1855, the county government was established in Carrollton and in 1858, the first courthouse was built. In 1869, the seat was moved to Carroll City (today Carroll) which was centrally located and connected to theChicago and North Western Transportation Company. The courthouse was destroyed in 1886 by fire. The present courthouse was erected in 1965. However the courthouse is set to go under construction in the near future.
According to theU.S. Census Bureau, the county has a total area of 570 square miles (1,500 km2), of which 569 square miles (1,470 km2) is land and 0.8 square miles (2.1 km2) (0.1%) is water.[5]
As of the2020 census, the county had a population of 20,760. The median age was 42.5 years, 24.0% of residents were under the age of 18, and 21.5% 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 94.0 males age 18 and over.[12]
There were 8,764 households in the county, of which 27.1% had children under the age of 18 living in them. Of all households, 51.0% were married-couple households, 18.9% were households with a male householder and no spouse or partner present, and 24.5% were households with a female householder and no spouse or partner present. About 32.8% of all households were made up of individuals and 15.7% had someone living alone who was 65 years of age or older. There were 9,490 housing units, of which 7.7% were vacant; among occupied housing units, 74.8% were owner-occupied and 25.2% were renter-occupied, with a 1.6% homeowner vacancy rate and a 9.2% rental vacancy rate.[12]
48.9% of residents lived in urban areas, while 51.1% lived in rural areas.[14]
The 2010 census recorded a population of 20,816 in the county, with a population density of36.6/sq mi (14.1/km2). There were 9,376 housing units, of which 8,683 were occupied.[15]
As of thecensus[16] of 2000, there were 21,421 people, 8,486 households, and 5,668 families residing in the county. Thepopulation density was 38 people per square mile (15 people/km2). There were 9,019 housing units at an average density of 16 units per square mile (6.2 units/km2). The racial makeup of the county was 98.87%White, 0.18%Black orAfrican American, 0.10%Native American, 0.34%Asian, 0.20% fromother races, and 0.31% from two or more races. 0.54% of the population wereHispanic orLatino of any race.
There were 8,486 households, out of which 32.90% had children under the age of 18 living with them, 57.00% weremarried couples living together, 6.80% had a female householder with no husband present, and 33.20% were non-families. 29.60% of all households were made up of individuals, and 15.50% had someone living alone who was 65 years of age or older. The average household size was 2.46 and the average family size was 3.07.
In the county, the population was spread out, with 26.90% under the age of 18, 7.40% from 18 to 24, 25.90% from 25 to 44, 21.00% from 45 to 64, and 18.70% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 95.10 males. For every 100 females age 18 and over, there were 92.00 males.
The median income for a household in the county was $37,275, and the median income for a family was $47,040. Males had a median income of $30,074 versus $21,528 for females. Theper capita income for the county was $18,595. About 4.50% of families and 6.50% of the population were below thepoverty line, including 6.10% of those under age 18 and 8.20% of those age 65 or over.