Carroll County, Illinois

Founding: 1839
Parent county: Jo Daviess

Namesake: Charles Carroll, Maryland politician
Seat: Savanna (1839–1843); Mount Carroll (1843–)

Land area: 445 square miles

Population (2020): 15,702

Population (historic): 1,023 (1840); 11,733 (1860); 16,976 (1880); 18,963 (1900); 18,433 (1930)

Periods of population growth: pre-1840–1900; 1910s; 1940–1960; 2010s

Subdivisions: Three cities; four villages; 12 townships

Pre-1940 residences (estimated): 3,161 (37.4%)
Pre-1940 housing survival rate: 61.9%
Pre-1860 housing survival rate (1940): 10.8%

Farm housing in disrepair (1950): 3.4%

Nonfarm housing in disrepair (1950): 5.3%

Average farmhouse value (1930): $2,258
Average outbuilding value (1930): $3,008

Average farmhouse size (1940): 7.3 rooms
Number of farms (1920): 1,769
Average farm size (1920): 127.1 acres
Sources of settlement: Pennsylvania, Germany, New York, Maryland, and Ireland
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Savanna (ex-seat)

Namesake: Prairies near the city site

Founding: 1828 (platting); 1835 (post office); 1874 (incorporation)

Population (2020): 2,783

Population (historic): 658 (1850); 971 (1870); 3,097 (1890); 3,691 (1910); 5,086 (1930)

Periods of population growth: pre-1850–1920; 1940s
Pre-1940 residences (estimated): 833 (49.4%)

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Mount Carroll

Namesake: Carroll County

Founding: 1841 (platting); 1845 (post office); 1867 (incorporation)

Population (2020): 1,717

Population (historic): 462 (1850); 1,756 (1870); 1,836 (1890); 1,759 (1910); 1,775 (1930)

Periods of population growth: 1841–1900; 1910s; 1930–1970; 1990s
Pre-1940 residences (estimated): 462 (55.6%)
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Outstanding Buildings

1. James Jones House (c. 1855). 27815 Georgetown Road. Cherry Grove–Shannon.
2. Joseph Steffens House (1843). 30849 Elkhorn Road. Elkhorn Grove.
3. Henry Harnish Farm (c. 1895). 16148 State Route 64. Mount Carroll. Queen Anne.
4. Alonzo Heath Farm (c. 1845). Telegraph Road, west of Dimont Road. Rock Creek–Lima. Greek Revival. Razed.
5. Charles Franks Farm (c. 1850). 34431 US Highway 52. Rock Creek–Lima.
6. Duncan MacKay House (c. 1855). 7824 Oakville Road. Salem. Greek Revival.

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