Winnebago County, Illinois

Founding: 1836
Parent counties: Jo Daviess and unorganized territory

Namesake: The Winnebago people
Seat: Rockford (1836–)

Land area: 513 square miles

Population (2020): 285,350

Population (historic): 4,609 (1840); 24,491 (1860); 30,505 (1880); 47,845 (1900); 117,373 (1930)

Periods of population growth: pre-1840–2010

Subdivisions: Three cities; eight villages; one CDP; 14 townships

Pre-1940 residences (estimated): 20,060 (16%)
Pre-1940 housing survival rate: 54.8%
Pre-1860 housing survival rate (1940): 14.2%

Farm housing in disrepair (1950): 4.3%

Nonfarm housing in disrepair (1950): 4.9%

Average farmhouse value (1930): $2,846
Average outbuilding value (1930): $3,058

Average farmhouse size (1940): 7.2 rooms
Number of farms (1920): 2,185
Average farm size (1920): 113.5 acres
Sources of settlement: New York, Sweden, Ireland, England, Pennsylvania, Wisconsin, and Scotland
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Rockford

Namesake: The Rock River

Founding: 1834 (platting as Midway); 1837 (post office); 1839 (incorporation)

Population (2020): 148,655

Population (historic): 6,979 (1860); 13,120 (1880); 31,051 (1900); 85,864 (1930)

Periods of population growth: 1834–1930; 1940–1970; 1990–2010
Pre-1940 residences (estimated): 16,252 (23.7%)
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