Mahaska County, Iowa

{{short description|County in Iowa, United States}} {{Use American English|date=June 2025}} {{Use mdy dates|date=April 2024}} {{Infobox U.S. county | county = Mahaska County | state = Iowa | ex image = Mahaska County, Iowa Courthouse.jpg | ex image size = 240px | ex image cap = The courthouse in Oskaloosa, built 1886, is on the NRHP. The architect was Henry C. Koch. | seal = | founded = February 17, 1843 | named for = Chief Mahaska | seat wl = Oskaloosa | largest city wl = Oskaloosa | area_total_sq_mi = 573 | area_land_sq_mi = 571 | area_water_sq_mi = 2.5 | area percentage = 0.4 | population_as_of = 2020 | population_total = 22190 | pop_est_as_of = 2025 | population_est = 21880 {{decrease}} | density_sq_mi = auto | time zone = Central | district = 1st | web = https://www.mahaskacountyia.gov/ | footnotes = * Iowa county number '''62'''<ref>{{cite web|title=Iowa County Names and Numbers |url=https://das.iowa.gov/media/3516/download?inline |publisher=Iowa Department of Administrative Services |access-date=February 9, 2026}}</ref> }} '''Mahaska County''' is a county located in the U.S. state of Iowa. As of the 2020 census, the population was 22,190.<ref name=cen2020>{{cite web |title=2020 Census State Redistricting Data |url=https://www2.census.gov/programs-surveys/decennial/2020/data/01-Redistricting_File--PL_94-171/Iowa/ |website=census.gov |publisher=United states Census Bureau |access-date=August 12, 2021}}</ref> The county seat is Oskaloosa.<ref name="NACo">{{cite web|title=Find a County |url=https://ce.naco.org/?find=true |publisher=National Association of Counties |access-date=February 9, 2026}}</ref>

Mahaska County comprises the Oskaloosa, IA Micropolitan Statistical Area.

==History== thumb|left|upright|Mahaska, from Fulton's ''Red Men of Iowa'' (1882) Mahaska County was formed in February 1843. The county has been self-governing since February 5, 1844. It was named after chief Mahaska of the Iowa people. The county was the first in Iowa to have a sheriff and a justice of peace.<ref name=MC>[http://www.iowacounties.org/About%20Us/AboutCoGov/County%20Pages/Mahaska.htm Mahaska County] {{webarchive|url=https://archive.today/20070703140822/http://www.iowacounties.org/About%20Us/AboutCoGov/County%20Pages/Mahaska.htm|date=July 3, 2007}}</ref>

The first courthouse was completed in January 1846. When a larger structure was required, the second courthouse was constructed in 1885–86, first being used on February 27, 1886. The first school, a small log cabin one-half mile (ca. 2 km) east of Oskaloosa, was opened on September 16, 1844, and the Cumberland Presbyterian Church opened as the first church in 1846.<ref>{{Cite web |url=http://www.mahaskacounty.org/about/about.html |title=About Mahaska |access-date=January 20, 2008 |archive-date=May 9, 2008 |archive-url=https://web.archive.org/web/20080509091956/http://www.mahaskacounty.org/about/about.html |url-status=dead }}</ref> On July 2, 1850, the first edition of the ''Iowa Herald'' was issued (today the ''Oskaloosa Herald''). The first tracks of the Des Moines Valley Railroad were laid through the county in 1864.<ref name=MC/>

Coal mining was once a major industry in Mahaska County.<ref>Map of [http://www.gis.centralareatechteam.org/img/org/Mahaska/Coal_Mines.jpg Historic Coal Mines in Mahaska County]{{dead link|date=January 2018|bot=InternetArchiveBot|fix-attempted=yes}}, Mahaska 4-H Tech Team, May 2006.</ref> During the 19th century, Muchakinock, about {{convert|5|mi|km}} south of Oskaloosa, was probably the largest and most prosperous coal camp in Iowa. {{clear left}}

==Geography== According to the United States Census Bureau, the county has a total area of {{convert|573|sqmi}}, of which {{convert|571|sqmi}} is land and {{convert|2.5|sqmi}} (0.4%) is water.<ref>{{cite web|url=https://www.census.gov/geographies/reference-files/time-series/geo/gazetteer-files.html|publisher=United States Census Bureau|access-date=April 23, 2011|date=February 12, 2011|title=US Gazetteer files: 2010, 2000, and 1990}}</ref>

===Major highways=== * x20px U.S. Highway 63 * x20px Iowa Highway 23 * x20px Iowa Highway 92 * x20px Iowa Highway 163 * x20px Iowa Highway 146 * x20px Iowa Highway 149

===Transit=== ===Adjacent counties=== * Jasper County (northwest) * Poweshiek County (north) * Keokuk County (east) * Wapello County (southeast) * Monroe County (southwest) * Marion County (west)

==Demographics== {{US Census population |1850= 5989 |1860= 14816 |1870= 22508 |1880= 25202 |1890= 28805 |1900= 34273 |1910= 29860 |1920= 26270 |1930= 25804 |1940= 26485 |1950= 24672 |1960= 23602 |1970= 22177 |1980= 22867 |1990= 21532 |2000= 22335 |2010= 22381 |2020= 22190 |estyear=2025 |estimate=21880 |estref=<ref name="USCensusEst2025">{{cite web|url=https://www.census.gov/data/tables/time-series/demo/popest/2020s-counties-total.html|title=County Population Totals and Components of Change: 2020-2025|publisher=United States Census Bureau|access-date=April 17, 2026}}</ref> {{decrease}} |align-fn=center |footnote=U.S. Decennial Census<ref>{{cite web|title=U.S. Decennial Census |url=https://www.census.gov/programs-surveys/decennial-census.html |publisher=United States Census Bureau |access-date=January 7, 2014}}</ref><br>1790–1960<ref>{{cite web|title=Historical Census Browser |url=http://mapserver.lib.virginia.edu |publisher=University of Virginia Library |url-status=live |date=2007 |access-date=January 7, 2014 |archive-url=https://web.archive.org/web/20091212224028/http://mapserver.lib.virginia.edu/ |archive-date=December 12, 2009}}</ref> 1900–1990<ref>{{cite web|last=Forstall |first=Richard L. |title=Population of Counties by Decennial Census: 1900 to 1990 |url=https://www.census.gov/population/cencounts/ia190090.txt |publisher=United States Census Bureau |url-status=live |date=April 20, 1995 |access-date=January 7, 2014 |archive-url=https://web.archive.org/web/19990219135447/http://www.census.gov/population/cencounts/ia190090.txt |archive-date=February 19, 1999}}</ref><br>1990–2000<ref>{{cite web|title=Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000 |url=https://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |url-status=live |publisher=United States Census Bureau |access-date=January 7, 2014 |archive-url=https://web.archive.org/web/20100327165705/http://www.census.gov/population/www/cen2000/briefs/phc-t4/tables/tab02.pdf |archive-date=March 27, 2010}}</ref> 2010–2020<ref name="QF">{{Cite web|title=U.S. Census Bureau QuickFacts: Mahaska County, Iowa |url=https://www.census.gov/quickfacts/fact/table/mahaskacountyiowa/PST045224 |access-date=February 9, 2026 |website=www.census.gov |language=en}}</ref> }}

===2020 census=== thumb|right|Population of Mahaska County from the U.S. census data As of the 2020 census, the county had a population of 22,190, a population density of {{Pop density|22190|571.430778|sqmi|km2|prec=1}}, and 96.02% of residents reported being of one race.<ref name="Census2020DP">{{cite web|title=2020 Decennial Census Demographic Profile (DP1)|url=https://api.census.gov/data/2020/dec/dp?get=NAME,DP1_0021P,DP1_0024P,DP1_0025C,DP1_0049C,DP1_0045C,DP1_0069C,DP1_0073C,DP1_0125P,DP1_0126P,DP1_0129P,DP1_0133P,DP1_0137P,DP1_0138P,DP1_0139P,DP1_0141P,DP1_0142P,DP1_0143P,DP1_0145P,DP1_0146P,DP1_0147C,DP1_0148C,DP1_0149C,DP1_0156C,DP1_0157C,DP1_0158C,DP1_0159P,DP1_0160P&for=county%3A123&in=state%3A19|website=United States Census Bureau|year=2021|access-date=December 25, 2025|df=mdy}}</ref><ref name="Census2020PL">{{cite web|title=2020 Decennial Census Redistricting Data (Public Law 94-171)|url=https://api.census.gov/data/2020/dec/pl?get=NAME,P1_001N,P1_003N,P1_004N,P1_005N,P1_006N,P1_007N,P1_008N,P1_009N,P2_001N,P2_002N,H1_001N,H1_002N&for=county%3A123&in=state%3A19|website=United States Census Bureau|year=2021|access-date=December 25, 2025|df=mdy}}</ref>

The median age was 39.7 years. 23.7% of residents were under the age of 18 and 19.3% of residents were 65 years of age or older. For every 100 females there were 99.2 males, and for every 100 females age 18 and over there were 97.2 males age 18 and over.<ref name="Census2020DP"/>

The racial makeup of the county was 92.2% White, 1.8% Black or African American, 0.2% American Indian and Alaska Native, 1.1% Asian, 0.1% Native Hawaiian and Pacific Islander, 0.7% from some other race, and 4.0% from two or more races. Hispanic or Latino residents of any race comprised 2.2% of the population.<ref name="Census2020PL"/>

56.5% of residents lived in urban areas, while 43.5% lived in rural areas.<ref name="Census2020DHC">{{cite web|title=2020 Decennial Census Demographic and Housing Characteristics (DHC)|url=https://api.census.gov/data/2020/dec/dhc?get=NAME,P2_002N,P2_003N&for=county%3A123&in=state%3A19|website=United States Census Bureau|year=2023|access-date=December 25, 2025|df=mdy}}</ref>

There were 8,799 households in the county, of which 29.7% had children under the age of 18 living in them. Of all households, 51.7% were married-couple households, 18.3% were households with a male householder and no spouse or partner present, and 22.9% were households with a female householder and no spouse or partner present. About 28.2% of all households were made up of individuals and 13.1% had someone living alone who was 65 years of age or older.<ref name="Census2020DP"/> There were 9,680 housing units, of which 9.1% were vacant. Among occupied housing units, 71.4% were owner-occupied and 28.6% were renter-occupied. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 7.1%.<ref name="Census2020DP"/>

===2010 census=== As of the 2010 census recorded a population of 22,381 in the county, with a population density of {{Pop density|22381|570.87|sqmi|km2|prec=1}}. There were 9,766 housing units, of which 8,975 were occupied.<ref>{{cite web|url=https://www2.census.gov/library/publications/decennial/2010/cph-2/cph-2-17.pdf |archive-url=https://web.archive.org/web/20201016010401/https://www2.census.gov/library/publications/decennial/2010/cph-2/cph-2-17.pdf |archive-date=October 16, 2020 |url-status=live|title=Population & Housing Occupancy Status 2010|publisher=United States Census Bureau – American FactFinder|access-date=August 15, 2022}}</ref>

===2000 census=== As of the 2000 census, there were 22,335 people, 8,880 households, and 6,144 families residing in the county. The population density was {{convert|39|/mi2|/km2|disp=preunit|people |people}}. There were 9,551 housing units at an average density of {{convert|17|/mi2|/km2|disp=preunit|units |units|}}. The racial makeup of the county was 97.20% White, 0.64% Black or African American, 0.19% Native American, 0.86% Asian, 0.03% Pacific Islander, 0.30% from other races, and 0.78% from two or more races. 0.85% of the population were Hispanic or Latino of any race.

There were 8,880 households, out of which 32.40% had children under the age of 18 living with them, 58.60% were married couples living together, 7.50% had a female householder with no husband present, and 30.80% were non-families. 26.60% of all households were made up of individuals, and 12.40% had someone living alone who was 65 years of age or older. The average household size was 2.45 and the average family size was 2.96.

In the county, the population was spread out, with 25.70% under the age of 18, 9.40% from 18 to 24, 26.80% from 25 to 44, 21.70% from 45 to 64, and 16.30% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 99.10 males. For every 100 females age 18 and over, there were 96.90 males.

The median income for a household in the county was $37,314, and the median income for a family was $43,557. Males had a median income of $32,618 versus $23,192 for females. The per capita income for the county was $18,232. About 7.50% of families and 9.80% of the population were below the poverty line, including 11.70% of those under age 18 and 9.30% of those age 65 or over.

==Communities== ===Cities=== {{div col}} * Barnes City * Beacon * Eddyville * Fremont * Keomah Village * Leighton * New Sharon * Oskaloosa * Rose Hill * University Park {{div col end}}

===Unincorporated communities=== {{div col}} * Cedar * Evans * Hopewell * Indianapolis * Lacey * Lakonta * Olivet * Peoria * Taintor * Tioga * Union Mills * Wright {{div col end}}

===Townships=== {{div col}} * Adams * Black Oak * Cedar * East Des Moines * Garfield * Harrison * Jefferson * Lincoln * Madison * Monroe * Pleasant Grove * Prairie * Richland * Scott * Spring Creek * Union * West Des Moines * White Oak {{div col end}}

===Population ranking=== The population ranking of the following table is based on the 2020 census of Mahaska County.<ref name=cen2020/>

'''†''' ''county seat''

{| class="wikitable sortable" |- ! Rank ! City/Town/etc. ! Municipal type ! Population<br>(2020 Census) ! Population<br>(2024 Estimate) |- style="background-color:#FFFACD;" | 1 |'''†''' '''Oskaloosa''' | City | 11,558 | 11,569 |- style="background-color:#FFFACD;" | 2 |'''New Sharon''' | City | 1,262 | 1,280 |- style="background-color:#FFFACD;" | 3 |'''Eddyville''' (''partially in Monroe and Wapello Counties'') | City | 970 | 984 |- style="background-color:#FFFACD;" | 4 |'''Fremont''' | City | 708 | 718 |- style="background-color:#FFFACD;" | 5 |'''University Park''' | City | 487 | 492 |- style="background-color:#FFFACD;" | 6 |'''Beacon''' | City | 445 | 455 |- style="background-color:#FFFACD;" | 7 |'''Leighton''' | City | 158 | 155 |- style="background-color:#FFFACD;" | 8 |'''Rose Hill''' | City | 157 | 153 |- style="background-color:#FFFACD;" | 9 |'''Barnes City''' (''partially in Poweshiek County'') | City | 156 | 151 |- style="background-color:#FFFACD;" | 10 |'''Keomah Village''' | City | 110 | 138 |}

==Politics== Mahaska County is a strongly Republican county. Only six Republican Party presidential candidates from 1880 to the present day have failed to win the county, most recently Barry Goldwater in 1964 in his landslide loss statewide & nationally to Lyndon B. Johnson. {{PresHead|place=Mahaska County, Iowa|whig=no|source1=<ref>{{Cite web|url=http://uselectionatlas.org/RESULTS|title=Dave Leip's Atlas of U.S. Presidential Elections|last=Leip|first=David|website=uselectionatlas.org|access-date=April 27, 2018}}</ref>}}  {{PresRow|1896|Republican|4,256|3,974|166|Iowa}} {{PresRow|1900|Republican|4,480|3,596|236|Iowa}} {{PresRow|1904|Republican|4,091|2,287|489|Iowa}} {{PresRow|1908|Republican|3,326|3,035|495|Iowa}} {{PresRow|1912|Democratic|1,682|2,576|2,190|Iowa}} {{PresRow|1916|Democratic|3,143|3,151|235|Iowa}} {{PresRow|1920|Republican|6,739|3,339|362|Iowa}} {{PresRow|1924|Republican|5,810|1,673|3,060|Iowa}} {{PresRow|1928|Republican|7,368|3,200|97|Iowa}} {{PresRow|1932|Democratic|4,655|5,586|472|Iowa}} {{PresRow|1936|Democratic|5,270|6,094|362|Iowa}} {{PresRow|1940|Republican|6,123|5,757|97|Iowa}} {{PresRow|1944|Republican|5,123|4,652|297|Iowa}} {{PresRow|1948|Democratic|4,238|4,327|465|Iowa}} {{PresRow|1952|Republican|7,369|3,745|409|Iowa}} {{PresRow|1956|Republican|6,864|3,965|205|Iowa}} {{PresRow|1960|Republican|7,129|3,746|26|Iowa}} {{PresRow|1964|Democratic|3,787|6,396|22|Iowa}} {{PresRow|1968|Republican|5,670|3,721|579|Iowa}} {{PresRow|1972|Republican|6,374|3,382|232|Iowa}} {{PresRow|1976|Republican|5,267|4,838|146|Iowa}} {{PresRow|1980|Republican|5,650|3,968|745|Iowa}} {{PresRow|1984|Republican|6,086|4,107|100|Iowa}} {{PresRow|1988|Republican|4,798|4,451|71|Iowa}} {{PresRow|1992|Republican|4,953|3,714|1,580|Iowa}} {{PresRow|1996|Republican|4,473|3,737|731|Iowa}} {{PresRow|2000|Republican|5,971|3,370|202|Iowa}} {{PresRow|2004|Republican|6,858|3,790|80|Iowa}} {{PresRow|2008|Republican|6,271|4,464|199|Iowa}} {{PresRow|2012|Republican|6,448|4,213|222|Iowa}} {{PresRow|2016|Republican|7,432|2,619|581|Iowa}} {{PresRow|2020|Republican|8,297|2,894|213|Iowa}} {{PresRow|2024|Republican|8,207|2,577|162|Iowa}} {{PresFoot}}

==References== {{Reflist|30em}}

==External links== {{Commons}} * [http://www.mahaskacounty.org Mahaska County website]

{{Geographic Location |Centre = Mahaska County, Iowa |North = Poweshiek County |Northeast = |East = Keokuk County |Southeast = Wapello County |South = |Southwest = Monroe County |West = Marion County |Northwest = Jasper County }}

{{Mahaska County, Iowa}} {{Iowa}} {{Authority control}} {{Coord|41|20|02|N|92|38|44|W|region:US-IA_type:adm2nd_source:dewiki|display=title}}

Category:Mahaska County, Iowa Category:Iowa placenames of Native American origin Category:1843 establishments in Iowa Territory Category:Populated places in the United States established in 1843