Johnson County, Illinois

Founding: 1812
Parent county: Randolph

Namesake: Richard Johnson, Kentucky politician
Seat: Elvira (1814–1818); Vienna (1818–)

Land area: 344 square miles

Population (2020): 13,308

Population (historic): 843 (1820); 4,114 (1850); 11,248 (1870); 15,667 (1900); 10,203 (1930)

Periods of population growth: pre-1820–1900; 1930s; 1960–2000; 2010s

Subdivisions: One city; six villages

Pre-1940 residences (estimated): 695 (12.3%)
Pre-1940 housing survival rate: 27.7%
Pre-1860 housing survival rate (1940): 1.4%

Farm housing in disrepair (1950): 23.1%

Nonfarm housing in disrepair (1950): 16.8%

Average farmhouse value (1930): $649
Average outbuilding value (1930): $481

Average farmhouse size (1940): 4.4 rooms
Number of farms (1920): 1,742
Average farm size (1920): 79.5 acres
Sources of settlement: Tennessee and Kentucky
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Vienna

Namesake: Unclear—perhaps Vienna, Austria

Founding: 1818 (platting); 1824 (post office); 1837 (incorporation)

Population (2020): 1,343

Population (historic): 142 (1850); 550 (1870); 828 (1890); 1,124 (1910); 874 (1930)

Periods of population growth: pre-1850–1870; 1880–1900; 1930s; 1950–1990; 2000s
Pre-1940 residences (estimated): 161 (19.9%)
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Outstanding Buildings

1. John DuPont House (1872). 130 West 5th Street. Italianate/Gothic Revival.

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