DeKalb County, Illinois

Founding: 1837
Parent county: Kane

Namesake: Johann de Kalb, Continental Army general
Seat: Sycamore (1837–)

Land area: 631 square miles

Population (2020): 100,420

Population (historic): 1,697 (1840); 19,086 (1860); 26,768 (1880); 31,756 (1900); 32,644 (1930)

Periods of population growth: pre-1840–1910; 1920–2010

Subdivisions: Four cities; one town; seven villages; 19 townships

Pre-1940 residences (estimated): 7,784 (18.9%)
Pre-1940 housing survival rate: 74%
Pre-1860 housing survival rate (1940): 11%

Farm housing in disrepair (1950): 6.7%

Nonfarm housing in disrepair (1950): 4.6%

Average farmhouse value (1930): $2,642
Average outbuilding value (1930): $3,966

Average farmhouse size (1940): 7.5 rooms
Number of farms (1920): 2,400
Average farm size (1920): 147.4 acres
Sources of settlement: New York, Pennsylvania, Germany, Sweden, Ireland, England, and Canada
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Sycamore

Namesake: Uncertain—presumably a sycamore grove near the city site

Founding: 1837 (platting); 1840 (post office); 1859 (incorporation)

Population (2020): 18,577

Population (historic): 338 (1850); 1,967 (1870); 2,987 (1890); 3,926 (1910); 4,021 (1930)

Periods of population growth: pre-1850–1880; 1890–1910; 1920–2020
Pre-1940 residences (estimated): 1,108 (15.9%)
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