Carroll County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 20,760. Its county seat is Carroll. The county is named in honor of Charles Carroll of Carrollton, signer of the Declaration of Independence.

Carroll County was formed on January 15, 1851, from sections of Pottawattamie County. It was named after Charles Carroll of Carrollton, 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 the Chicago 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 the U.S. Census Bureau, the county has a total area of 570 square miles (1,500 km), of which 569 square miles (1,470 km) is land and 0.8 square miles (2.1 km) (0.1%) is water.

• U.S. Highway 30
• U.S. Highway 71
• Iowa Highway 141

• Sac County (northwest)
• Calhoun County (northeast)
• Greene County (east)
• Guthrie County (southeast)
• Audubon County (south)
• Crawford County (west)

Historical population

Census	Pop.	Note	%±
1860	281		—
1870	2,451		772.2%
1880	12,351		403.9%
1890	18,825		52.4%
1900	20,319		7.9%
1910	20,117		−1.0%
1920	21,549		7.1%
1930	22,326		3.6%
1940	22,770		2.0%
1950	23,065		1.3%
1960	23,431		1.6%
1970	22,912		−2.2%
1980	22,951		0.2%
1990	21,423		−6.7%
2000	21,421		0.0%
2010	20,816		−2.8%
2020	20,760		−0.3%
2023 (est.)	20,522		−1.1%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2018

The 2020 census recorded a population of 20,760 in the county, with a population density of 35.845/sq mi (13.840/km). 97.14% of the population reported being of one race. 91.28% were non-Hispanic White, 1.26% were Black, 2.86% were Hispanic, 0.15% were Native American, 0.36% were Asian, 0.00% were Native Hawaiian or Pacific Islander and 4.08% were some other race or more than one race. There were 9,490 housing units of which 8,764 were occupied.

The 2010 census recorded a population of 20,816 in the county, with a population density of 36.58/sq mi (14.125/km). There were 9,376 housing units, of which 8,683 were occupied.

As of the census of 2000, there were 21,421 people, 8,486 households, and 5,668 families residing in the county. The population density was 38 people per square mile (15 people/km). There were 9,019 housing units at an average density of 16 units per square mile (6.2 units/km). The racial makeup of the county was 98.87% White, 0.18% Black or African American, 0.10% Native American, 0.34% Asian, 0.20% from other races, and 0.31% from two or more races. 0.54% of the population were Hispanic or Latino 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% were married 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. The per capita income for the county was $18,595. About 4.50% of families and 6.50% of the population were below the poverty line, including 6.10% of those under age 18 and 8.20% of those age 65 or over.

Carroll County is divided into sixteen townships:

The population ranking of the following table is based on the 2020 census of Carroll County. † county seat

Rank	City/Town/etc.	Municipal type	Population (2020 Census)
1	† Carroll	City	10,321
2	Manning	City	1,455
3	Coon Rapids (partially in Guthrie County)	City	1,300
4	Glidden	City	1,151
5	Arcadia	City	525
6	Breda	City	500
7	Templeton	City	352
8	Dedham	City	224
9	Halbur	City	243
10	Lidderdale	City	166
11	Lanesboro	City	119
12	Ralston (partially in Greene County)	City	76 (81 total)
13	Willey	City	73

United States presidential election results for Carroll County, Iowa

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	7,814	70.14%	3,153	28.30%	173	1.55%
2020	7,737	68.26%	3,454	30.47%	144	1.27%
2016	6,638	62.96%	3,309	31.38%	597	5.66%
2012	5,601	52.47%	4,947	46.35%	126	1.18%
2008	4,922	47.35%	5,302	51.01%	171	1.65%
2004	5,762	54.75%	4,689	44.56%	73	0.69%
2000	4,879	50.99%	4,463	46.65%	226	2.36%
1996	3,392	38.59%	4,333	49.29%	1,065	12.12%
1992	3,439	36.30%	3,800	40.11%	2,236	23.60%
1988	3,701	39.91%	5,437	58.63%	135	1.46%
1984	5,021	49.83%	4,960	49.22%	96	0.95%
1980	5,017	51.53%	3,885	39.90%	835	8.58%
1976	4,094	42.61%	5,333	55.51%	181	1.88%
1972	4,415	47.55%	4,608	49.63%	262	2.82%
1968	3,927	42.68%	4,809	52.26%	466	5.06%
1964	2,387	23.39%	7,807	76.49%	13	0.13%
1960	4,648	39.66%	7,064	60.27%	9	0.08%
1956	5,816	53.29%	5,085	46.60%	12	0.11%
1952	7,473	64.27%	4,139	35.60%	16	0.14%
1948	3,974	40.61%	5,711	58.36%	101	1.03%
1944	4,833	50.04%	4,799	49.68%	27	0.28%
1940	5,376	49.22%	5,526	50.59%	21	0.19%
1936	3,259	31.03%	6,285	59.84%	959	9.13%
1932	2,265	23.84%	7,174	75.52%	60	0.63%
1928	4,014	39.47%	6,134	60.32%	21	0.21%
1924	3,590	41.06%	1,994	22.80%	3,160	36.14%
1920	6,320	72.89%	2,174	25.07%	177	2.04%
1916	2,408	53.10%	2,085	45.98%	42	0.93%
1912	664	15.51%	2,326	54.32%	1,292	30.17%
1908	1,865	41.93%	2,510	56.43%	73	1.64%
1904	2,290	51.22%	2,040	45.63%	141	3.15%
1900	2,224	47.34%	2,434	51.81%	40	0.85%
1896	2,066	45.67%	2,417	53.43%	41	0.91%

• National Register of Historic Places listings in Carroll County, Iowa

• Carroll County government's website Archived July 20, 2018, at the Wayback Machine
• St. Anthony Regional Hospital

42°02′14″N 94°51′32″W / 42.03722°N 94.85889°W / 42.03722; -94.85889