Wapello County is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 35,437. The county seat is Ottumwa. The county was formed on February 17, 1843, and named for Wapello, a Meskwaki chief.

Wapello County is included in the Ottumwa, IA Micropolitan Statistical Area.

According to the U.S. Census Bureau, the county has a total area of 436 square miles (1,130 km), of which 432 square miles (1,120 km) is land and 4.2 square miles (11 km) (1.0%) is water.

• U.S. Highway 34
• U.S. Highway 63
• Iowa Highway 16
• Iowa Highway 137
• Iowa Highway 149

• Ottumwa station
• Ottumwa Transit Authority

• Mahaska County (northwest)
• Keokuk County (northeast)
• Jefferson County (east)
• Davis County (south)
• Monroe County (west)

Historical population

Census	Pop.	Note	%±
1850	8,471		—
1860	14,518		71.4%
1870	22,346		53.9%
1880	25,285		13.2%
1890	30,426		20.3%
1900	35,426		16.4%
1910	37,743		6.5%
1920	37,937		0.5%
1930	40,480		6.7%
1940	44,280		9.4%
1950	47,397		7.0%
1960	46,126		−2.7%
1970	42,149		−8.6%
1980	40,241		−4.5%
1990	35,696		−11.3%
2000	36,051		1.0%
2010	35,625		−1.2%
2020	35,437		−0.5%
2023 (est.)	35,166		−0.8%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2018

The 2020 census recorded a population of 35,437 in the county, with a population density of 81.2225/sq mi (31.3602/km). There were 15,734 housing units, of which 14,167 were occupied.

Wapello County Racial Composition

Race	Num.	Perc.
White (NH)	27,295	77.02%
Black or African American (NH)	1,443	4.1%
Native American (NH)	66	0.2%
Asian (NH)	622	1.8%
Pacific Islander (NH)	518	1.5%
Other/Mixed (NH)	1,161	3.3%
Hispanic or Latino	4,332	12.22%

The 2010 census recorded a population of 35,625 in the county, with a population density of 82.5016/sq mi (31.8540/km). There were 16,098 housing units, of which 14,552 were occupied.

As of the census of 2000, there were 36,051 people, 14,784 households, and 9,801 families residing in the county. The population density was 84 people per square mile (32 people/km). There were 15,873 housing units at an average density of 37 units per square mile (14 units/km). The racial makeup of the county was 96.28% White, 0.93% Black or African American, 0.28% Native American, 0.65% Asian, 0.02% Pacific Islander, 1.05% from other races, and 0.79% from two or more races. 2.22% of the population were Hispanic or Latino of any race.

There were 14,784 households, out of which 28.80% had children under the age of 18 living with them, 52.70% were married couples living together, 9.90% had a female householder with no husband present, and 33.70% were non-families. 28.20% of all households were made up of individuals, and 13.40% had someone living alone who was 65 years of age or older. The average household size was 2.37 and the average family size was 2.89.

In the county, the population was spread out, with 23.30% under the age of 18, 9.70% from 18 to 24, 26.00% from 25 to 44, 23.30% from 45 to 64, and 17.80% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 94.80 males. For every 100 females age 18 and over, there were 91.70 males.

The median income for a household in the county was $32,188, and the median income for a family was $39,224. Males had a median income of $31,346 versus $21,286 for females. The per capita income for the county was $16,500. About 9.40% of families and 13.20% of the population were below the poverty line, including 18.00% of those under age 18 and 7.90% of those age 65 or over.

• Agency
• Blakesburg
• Chillicothe
• Eddyville
• Eldon
• Kirkville
• Ottumwa

The population ranking of the following table is based on the 2020 census of Wapello County.

† county seat

Rank	City/Town/etc.	Municipal type	Population (2020 Census)
1	† Ottumwa	City	25,529
2	Eddyville (partially in Mahaska and Monroe Counties)	City	970
3	Eldon	City	783
4	Agency	City	620
5	Blakesburg	City	274
6	Kirkville	City	157
7	Chillicothe	City	76

Between 1864 and 1928, Wapello County backed the Republican candidate in every election except 1912, when former Republican Theodore Roosevelt ran as the Progressive candidate, fracturing the Republican party and allowing Democrat Woodrow Wilson to take the county with a plurality of the vote of less than 37%. From 1932 to 2012, the county voted Democratic in every election except two, the nationwide Republican landslides of Dwight D. Eisenhower in 1952 and Richard Nixon in 1972. Beginning in 2016, Wapello County has shifted back to the Republican column, as Donald Trump carried the county in each of his three runs, winning by a margin of over 20% in 2016 and over 23% in 2020, and over 31% in 2024. Also in 2024, Trump became the first candidate from any party to obtain at least 65% of the county's vote since Lyndon B. Johnson in 1964, and the first Republican to do so since Herbert Hoover in 1928.

United States presidential election results for Wapello County, Iowa

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	9,479	65.00%	4,896	33.57%	208	1.43%
2020	9,516	60.87%	5,821	37.24%	296	1.89%
2016	8,715	57.53%	5,594	36.93%	840	5.54%
2012	6,789	43.05%	8,663	54.93%	318	2.02%
2008	6,663	41.80%	8,820	55.33%	457	2.87%
2004	7,403	44.31%	9,125	54.62%	179	1.07%
2000	6,313	41.70%	8,355	55.19%	471	3.11%
1996	4,828	32.69%	8,437	57.12%	1,505	10.19%
1992	4,852	30.17%	8,670	53.91%	2,561	15.92%
1988	5,350	34.14%	10,177	64.93%	146	0.93%
1984	7,098	39.88%	10,545	59.24%	157	0.88%
1980	7,475	42.31%	8,923	50.50%	1,270	7.19%
1976	6,786	39.30%	10,249	59.35%	233	1.35%
1972	9,301	51.19%	8,348	45.94%	522	2.87%
1968	7,825	41.96%	9,375	50.28%	1,447	7.76%
1964	5,524	28.26%	13,971	71.48%	51	0.26%
1960	11,036	49.79%	11,116	50.15%	15	0.07%
1956	10,401	48.65%	10,960	51.26%	20	0.09%
1952	11,571	52.24%	10,449	47.17%	130	0.59%
1948	7,875	41.50%	10,841	57.13%	260	1.37%
1944	8,244	43.19%	10,732	56.22%	113	0.59%
1940	9,039	43.03%	11,880	56.56%	87	0.41%
1936	7,647	41.31%	10,578	57.14%	287	1.55%
1932	7,256	42.49%	9,504	55.66%	316	1.85%
1928	11,586	66.10%	5,793	33.05%	149	0.85%
1924	9,870	56.96%	3,039	17.54%	4,420	25.51%
1920	9,884	67.99%	4,131	28.42%	522	3.59%
1916	4,398	47.65%	3,994	43.28%	837	9.07%
1912	2,755	32.53%	3,102	36.62%	2,613	30.85%
1908	4,541	50.69%	3,724	41.57%	694	7.75%
1904	4,912	60.60%	2,473	30.51%	720	8.88%
1900	4,742	53.21%	3,902	43.78%	268	3.01%
1896	4,319	50.75%	4,041	47.49%	150	1.76%

• Big 4 Fair Art Hall, located at the Wapello County Fairgrounds
• Wapello County Courthouse
• National Register of Historic Places listings in Wapello County, Iowa

• Official Wapello County website

41°01′46″N 92°24′32″W / 41.02944°N 92.40889°W / 41.02944; -92.40889