Washington County, Illinois

Founding: 1818
Parent county: St. Clair

Namesake: George Washington, U.S. president
Seat: Covington (1818–1831); Nashville (1831–)

Land area: 563 square miles

Population (2020): 13,761

Population (historic): 1,517 (1820); 6,953 (1850); 17,599 (1870); 19,526 (1900); 16,286 (1930)

Periods of population growth: pre-1820–1880; 1890s; 1960–1980; 1990s

Subdivisions: Three cities; ten villages; 16 townships

National Register listings: Three

Pre-1940 residences (estimated): 1,544 (23.3%)
Pre-1940 housing survival rate: 40%
Pre-1860 housing survival rate (1940): 7.7%

Farm housing in disrepair (1950): 13.4%

Nonfarm housing in disrepair (1950): 10.4%

Average farmhouse value (1930): $1,147
Average outbuilding value (1930): $930

Average farmhouse size (1940): 5.2 rooms
Number of farms (1920): 2,357
Average farm size (1920): 113.8 acres
Sources of settlement: Germany, Missouri, Tennessee, and Kentucky
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Nashville

Namesake: Nashville, Tennessee

Founding: 1830 (platting as New Nashville); 1831 (post office); 1853 (incorporation)

Population (2020): 3,105

Population (historic): 872 (1860); 2,222 (1880); 2,184 (1900); 2,243 (1930)

Periods of population growth: pre-1860–1880; 1890s; 1910–1990; 2000s
Pre-1940 residences (estimated): 288 (21.8%)
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Outstanding Buildings

1. *St. John's Lutheran Church (1863). 18049 State Route 127. Hoyleton. Gothic Revival.
2. *John Hood House (1843). 1602 County Road 16. Oakdale.
3. *Olive Branch Lutheran Church (c. 1890). 11265 State Route 177. Okawville. Gothic Revival.
4. *St. John's Evangelical Church (c. 1895). 9971 Plum Hill Church Road. Plum Hill. Romanesque.