Poweshiek County is a county in the southeastern part of the U.S. state of Iowa. As of the 2020 census, the population was 18,662. The county seat is Montezuma. The county is named for the chief of the Fox tribe who signed the treaty ending the Black Hawk War. It lies along Interstate 80 between Des Moines and Iowa City. Poweshiek County's largest city is Grinnell.

Poweshiek County was formed in 1843. It was named for Meskwaki Chief Poweshiek (1791–1854), a chief of the Meskwaki people. The Poweshiek County Courthouse, completed in 1859, is listed on the National Register of Historic Places.

County business is overseen by three elected county supervisors. The county website provides names and contact information for the current supervisors.

• County Supervisors: Diana Dawley (D), Jason Roudabush (D), Jeff Tindle (R)
• County Attorney: Bart Klaver (R)
• County Auditor: Missy Eilander (R)
• County Recorder: Dianna Longhenry (R)
• County Sheriff: Tom Kriegel (D)
• County Treasurer: Sandy Ross (R)

United States presidential election results for Poweshiek County, Iowa

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2020	5,657	55.79%	4,306	42.47%	177	1.75%
2016	4,946	50.30%	4,304	43.77%	583	5.93%
2012	4,424	44.35%	5,357	53.70%	194	1.94%
2008	4,340	43.26%	5,519	55.01%	174	1.73%
2004	4,965	49.20%	5,043	49.98%	83	0.82%
2000	4,396	48.95%	4,222	47.02%	362	4.03%
1996	3,221	39.21%	4,183	50.93%	810	9.86%
1992	3,245	35.87%	4,056	44.83%	1,746	19.30%
1988	3,683	42.70%	4,876	56.53%	66	0.77%
1984	4,715	53.04%	4,103	46.16%	71	0.80%
1980	4,598	50.52%	3,529	38.77%	975	10.71%
1976	4,194	48.01%	4,360	49.91%	181	2.07%
1972	4,785	55.33%	3,718	42.99%	145	1.68%
1968	4,470	55.10%	3,250	40.06%	392	4.83%
1964	3,109	37.31%	5,213	62.55%	12	0.14%
1960	5,232	58.76%	3,671	41.23%	1	0.01%
1956	5,145	58.81%	3,602	41.17%	2	0.02%
1952	6,105	64.28%	3,318	34.93%	75	0.79%
1948	3,888	46.37%	4,324	51.57%	173	2.06%
1944	4,186	49.47%	4,234	50.04%	41	0.48%
1940	4,773	49.66%	4,794	49.88%	44	0.46%
1936	4,037	44.88%	4,745	52.75%	214	2.38%
1932	3,490	41.77%	4,649	55.64%	216	2.59%
1928	5,212	63.95%	2,787	34.20%	151	1.85%
1924	4,414	53.57%	1,428	17.33%	2,397	29.09%
1920	5,806	71.41%	2,125	26.14%	199	2.45%
1916	2,748	57.39%	1,880	39.26%	160	3.34%
1912	902	19.85%	1,631	35.89%	2,012	44.27%
1908	2,794	59.73%	1,661	35.51%	223	4.77%
1904	3,137	67.48%	1,212	26.07%	300	6.45%
1900	3,199	63.05%	1,765	34.79%	110	2.17%
1896	2,969	58.49%	2,013	39.66%	94	1.85%

Poweshiek County is served by Grinnell Regional Medical Center, an acute care hospital licensed for 81 beds. GRMC was established in 1967 after the merger of two hospitals.

According to the U.S. Census Bureau, the county has a total area of 586 square miles (1,520 km), of which 585 square miles (1,520 km) is land and 1.1 square miles (2.8 km) (0.2%) is water. It is drained by the north fork of Skunk River, which crosses the southwest corner, and by English River and other streams.

• Interstate 80
• U.S. Highway 6
• U.S. Highway 63
• Iowa Highway 21
• Iowa Highway 85
• Iowa Highway 146

• List of intercity bus stops in Iowa

• Tama County (north)
• Iowa County (east)
• Keokuk County (southeast)
• Mahaska County (south)
• Jasper County (west)

Historical population

Census	Pop.	Note	%±
1850	615		—
1860	5,668		821.6%
1870	15,581		174.9%
1880	18,936		21.5%
1890	18,394		−2.9%
1900	19,414		5.5%
1910	19,589		0.9%
1920	19,910		1.6%
1930	18,727		−5.9%
1940	18,758		0.2%
1950	19,344		3.1%
1960	19,300		−0.2%
1970	18,803		−2.6%
1980	19,306		2.7%
1990	19,033		−1.4%
2000	18,815		−1.1%
2010	18,914		0.5%
2020	18,662		−1.3%
2023 (est.)	18,453		−1.1%
U.S. Decennial Census 1790-1960 1900-1990 1990-2000 2010-2018

The 2020 census recorded a population of 18,662 in the county, with a population density of 31.7989/sq mi (12.2776/km). 96.55% of the population reported being of one race. There were 8,906 housing units, of which 7,536 were occupied.

Poweshiek County Racial Composition

Race	Num.	Perc.
White (NH)	17,004	91.11%
Black or African American (NH)	320	1.7%
Native American (NH)	53	0.3%
Asian (NH)	221	1.2%
Pacific Islander (NH)	21	0.11%
Other/Mixed (NH)	514	2.8%
Hispanic or Latino	529	2.83%

The 2010 census recorded a population of 18,914 in the county, with a population density of 32.3300/sq mi (12.4827/km). There were 8,949 housing units, of which 7,555 were occupied.

As of the census of 2000, there were 18,815 people, 7,398 households, and 4,882 families in the county. The population density was 32 people per square mile (12 people/km). There were 8,556 housing units at an average density of 15 per square mile (5.8/km). The racial makeup of the county was 96.74% White, 0.55% Black or African American, 0.23% Native American, 1.07% Asian, 0.05% Pacific Islander, 0.49% from other races, and 0.87% from two or more races. 1.20% of the population were Hispanic or Latino of any race.

Of the 7,398 households 29.0% had children under the age of 18 living with them, 55.8% were married couples living together, 7.4% had a female householder with no husband present, and 34.0% were non-families. 29.2% of households were one person and 13.9% were one person aged 65 or older. The average household size was 2.35 and the average family size was 2.88.

The age distribution was 22.7% under the age of 18, 12.8% from 18 to 24, 24.4% from 25 to 44, 22.5% from 45 to 64, and 17.6% 65 or older. The median age was 38 years. For every 100 females there were 92.5 males. For every 100 females age 18 and over, there were 88.8 males.

The median household income was $37,836 and the median family income was $46,599. Males had a median income of $32,781 versus $22,465 for females. The per capita income for the county was $18,629. About 6.2% of families and 9.8% of the population were below the poverty line, including 12.0% of those under age 18 and 5.9% of those age 65 or over.

Poweshiek County is served by three community school districts:

District	Location	Num of campuses (inc. parochial)	Num of students	Student– teacher ratio	High school	District web site
BGM Community School District (Brooklyn–Guernsey–Malcom)	Brooklyn	1	532	-	BGM	BGM
Grinnell–Newburg Community School District	Grinnell	6	1,475	-	Grinnell	Grinnell
Montezuma Community School District	Montezuma	1	537	-	Montezuma	Montezuma

Poweshiek County is home to Grinnell College, a small liberal arts college founded in 1846.

There is one private school in the county, Central Iowa Christian School, in Grinnell.

• Ewart

• Holiday Lake

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

† county seat

Rank	City/town/etc.	Municipal type	Population (2020 Census)
1	Grinnell	City	9,564
2	Brooklyn	City	1,502
3	† Montezuma	City	1,442
4	Victor (mostly in Iowa County)	City	875
5	Holiday Lake	CDP	473
6	Malcom	City	270
7	Deep River	City	249
8	Barnes City (partially in Mahaska County)	City	156
9	Searsboro	City	129
10	Hartwick	City	92
11	Guernsey	City	63

• Poweshiek County Courthouse
• National Register of Historic Places listings in Poweshiek County, Iowa

• Poweshiek County Official County website

41°41′03″N 92°31′48″W / 41.68417°N 92.53000°W / 41.68417; -92.53000