Johnson County, Iowa

Founding: 1838 (declared in 1837)
Parent counties: Cook, Dubuque, Muscatine, and unorganized territory

Namesake: Richard Johnson, U.S. vice president
Seat: Napoleon (1838–1839); Iowa City (1839–)

Land area: 614 square miles

Population (2020): 152,854

Population (historic): 4,472 (1850); 24,898 (1870); 23,082 (1890); 25,914 (1910); 30,276 (1930)

Periods of population growth: pre-1850–1880; 1890–2020

Subdivisions: 11 cities; one CDP; 20 townships

Pre-1940 residences (estimated): 7,349 (11.1%)
Pre-1940 housing survival rate: 69.1%
Pre-1860 housing survival rate (1940): 5.3%

Farm housing in disrepair (1950): 2.9%

Nonfarm housing in disrepair (1950): 2.7%

Average farmhouse value (1930): $2,561
Average outbuilding value (1930): $3,078
Average farmhouse size (1940): 6.7 rooms
Number of farms (1920): 2,625
Average farm size (1920): 122.1 acres
Sources of settlement: Czechoslovakia, Ohio, Pennsylvania, Germany, Ireland, and New York
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Iowa City

Namesake: The state of Iowa

Founding: 1839 (platting); 1839 (post office); 1853 (incorporation)

Population (2020): 74,828

Population (historic): 1,250 (1850); 5,914 (1870); 7,016 (1890); 10,091 (1910); 15,340 (1930)

Periods of population growth: 1839–1880; 1890–2020
Pre-1940 residences (estimated): 4,910 (13.5%)
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Outstanding Buildings

1. John McCune Farm (c. 1860). 5125 Sutliff Road. Cedar.
2. Sts. Peter and Paul Catholic Church (1916–1917). 1165 Taft Road. Cedar. Romanesque.
3. James McCollister House (1864/1880). 2460 South Gilbert Street. East Lucas. Italianate.
4. Sylvanus Johnson House (1856–1857). 2155 Prairie du Chien Road. East Lucas. Second Empire.
5. River Junction Store (c. 1885). 6090 River Junction Road. Fremont. Romanesque.
6. James Coulter Farm (c. 1875). 5453 Strawbridge Road. Graham. Italianate.
7. George Chadima Farm (c. 1895). 1097 Echo Road. Monroe. Queen Anne.
8. John Oaks House (1878). 2433 Cemetery Road. Oxford. Italianate.
9. Iowa Valley Farm / Michael Hetz Farm (c. 1865). Grabin Road, east of Black Hawk Road. Oxford. Italianate. Razed.
10. Frederick Weeber Farm (c. 1865). 4843 Kansas Road. Sharon.
11. Daniel Yoder House (c. 1875). 1453 540th Road. Washington.

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