Alexander County, Illinois

Founding: 1819
Parent county: Unorganized territory

Namesake: William Alexander, local physician
Seat: America (1819–1833); Unity (1833–1843); Thebes (1843–1860); Cairo (1860–)

Land area: 236 square miles

Population (2020): 5,240

Population (historic): 626 (1820); 2,484 (1850); 10,564 (1870); 19,384 (1900); 22,542 (1930)

Periods of population growth: pre-1820–1840; 1850–1920; 1930s; 1970s

Subdivisions: One city; four villages; one CDP; six precincts

National Register listings: Seven

Pre-1940 residences (estimated): 1,310 (32.9%)
Pre-1940 housing survival rate: 13%
Pre-1860 housing survival rate (1940): 11.2%

Farm housing in disrepair (1950): 17.3%

Nonfarm housing in disrepair (1950): 20.5%
Average farmhouse value (1930): $718
Average outbuilding value (1930): $640

Average farmhouse size (1940): 4 rooms
Number of farms (1920): 731
Average farm size (1920): 85.3 acres
Sources of settlement: Tennessee, Kentucky, Missouri, and Ireland
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Cairo

Namesake: Cairo, Egypt

Founding: 1839 (post office); 1846 (platting); 1857 (incorporation)

Population (2020): 1,733

Population (historic): 242 (1850); 6,267 (1870); 10,324 (1890); 14,548 (1910); 13,532 (1930)

Periods of population growth: 1846–1920; 1930s
Pre-1940 residences (estimated): 920 (53.1%)
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Outstanding Buildings

1. *Thomas McClure Farm (1882). 37769 Grapevine Trail. Queen Anne.