Mercer County, Illinois

Founding: 1835 (declared in 1825)
Parent county: Unorganized territory

Namesake: Hugh Mercer, Continental Army general
Seat: Millersburg (1835–1857); Aledo (1857–)

Land area: 561 square miles

Population (2020): 15,699

Population (historic): 2,352 (1840); 15,042 (1860); 19,502 (1880); 20,945 (1900); 16,641 (1930)

Periods of population growth: 1830–1880; 1890s; 1930s; 1960–1980

Subdivisions: Three cities; nine villages; 15 townships

Pre-1940 residences (estimated): 2,941 (39.7%)
Pre-1940 housing survival rate: 55.2%
Pre-1860 housing survival rate (1940): 8.2%

Farm housing in disrepair (1950): 5.1%

Nonfarm housing in disrepair (1950): 5.9%

Average farmhouse value (1930): $2,738
Average outbuilding value (1930): $2,795

Average farmhouse size (1940): 6.7 rooms
Number of farms (1920): 2,022
Average farm size (1920): 129.7 acres
Sources of settlement: Pennsylvania, Ohio, Sweden, Indiana, and Ireland
_________________________________________________________________________________

Aledo

Namesake: Unknown

Founding: 1856 (platting); 1856 (post office); 1863 (incorporation)

Population (2020): 3,633

Population (historic): 563 (1860); 1,492 (1880); 2,081 (1900); 2,203 (1930)

Periods of population growth: 1856–1920; 1930–1980; 2000s
Pre-1940 residences (estimated): 584 (34.6%)
_________________________________________________________________________________

View and filter the data. Or see a map.
_________________________________________________________________________________