Mahaska County, Iowa

 

Founding: 1844 (declared in 1843)
Parent counties: Keokuk and unorganized territory

Namesake: Mahaska, Iowa chief
Seat: Oskaloosa (1844–)

Land area: 571 square miles

Population (2020): 22,190

Population (historic): 5,989 (1850); 22,508 (1870); 28,805 (1890); 29,860 (1910); 25,804 (1930)

Periods of population growth: pre-1850–1900; 1930s; 1970s; 1990–2010

Subdivisions: Ten cities; 18 townships

Pre-1940 residences (estimated): 3,552 (36%)
Pre-1940 housing survival rate: 44.8%
Pre-1860 housing survival rate (1940): 8.8%

Farm housing in disrepair (1950): 5.3%

Nonfarm housing in disrepair (1950): 6.4%

Average farmhouse value (1930): $2,139
Average outbuilding value (1930): $2,026
Average farmhouse size (1940): 6.4 rooms
Number of farms (1920): 2,784
Average farm size (1920): 105.5 acres
Sources of settlement: Ohio, Illinois, Pennsylvania, Indiana, New York, Missouri, Virginia, and Kentucky
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Oskaloosa

Namesake: Uncertain—perhaps a mythical Creek figure

Founding: 1844 (platting); 1844 (post office); 1853 (incorporation)

Population (2020): 11,558

Population (historic): 625 (1850); 3,204 (1870); 6,558 (1890); 9,466 (1910); 10,123 (1930)

Periods of population growth: 1844–1860; 1870–1910; 1920–1950; 1960s; 1990–2020
Pre-1940 residences (estimated): 1,939 (35.8%)
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Outstanding Buildings

1. John Vorhees Farm (1871). 1261 185th Road. Black Oak. Italianate.
2. Maas Van Donselaar Farm (c. 1875). 1825 Barrows Road. Black Oak. Italianate.
3. Anna Van Donselaar Farm (c. 1870). 1051 State Route 163. Black Oak. Italianate.
4. Daniel Nelson Farm (1853). 2211 Nelson Lane. Spring Creek.

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