Iowa County, Iowa

Founding: 1845 (declared in 1843)
Parent county: Keokuk

Namesake: The Iowa River
Seat: Marengo (1845–)

Land area: 586 square miles

Population (2020): 16,662

Population (historic): 822 (1850); 16,644 (1870); 18,270 (1890); 18,409 (1910); 17,332 (1930)

Periods of population growth: pre-1850–1880; 1890s; 1910s; 1950s; 1990–2020

Subdivisions: Seven cities; eight CDPs; 16 townships

National Register listings: 11

Pre-1940 residences (estimated): 2,351 (32%)
Pre-1940 housing survival rate: 60.7%

Pre-1860 housing survival rate (1940): 5%

Farm housing in disrepair (1950): 1.5%

Nonfarm housing in disrepair (1950): 2.3%

Average farmhouse value (1930): $2,581
Average outbuilding value (1930): $2,972
Average farmhouse size (1940): 6.8 rooms
Number of farms (1920): 2,256
Average farm size (1920): 138.3 acres
Sources of settlement: Germany, Ohio, Illinois, New York, Pennsylvania, and Ireland
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Marengo

Namesake: The Battle of Marengo, fought during the Napoleonic Wars

Founding: 1845 (platting); 1846 (post office); 1859 (incorporation)

Population (2020): 2,435

Population (historic): 50 (1850); 1,693 (1870); 1,710 (1890); 1,786 (1910); 2,112 (1930)

Periods of population growth: 1845–1880; 1890s; 1910–1940; 1950s; 1970s; 1990s
Pre-1940 residences (estimated): 520 (42.9%)
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Outstanding Buildings

1. William Callahan Farm (c. 1895). 2729 110th Road. Washington. Eastlake.