Warren County, Illinois

Founding: 1831 (declared in 1825)
Parent county: Unorganized territory

Namesake: Joseph Warren, Boston revolutionary leader
Seat: Monmouth (1831–)

Land area: 542 square miles

Population (2020): 16,835

Population (historic): 308 (1830); 8,176 (1850); 23,174 (1870); 23,163 (1900); 21,745 (1930)

Periods of population growth: 1830–1870; 1890–1910; 1920s; 1940s; 1960–1980

Subdivisions: One city; four villages; 15 townships

Pre-1940 residences (estimated): 3,214 (41.8%)
Pre-1940 housing survival rate: 51.9%
Pre-1860 housing survival rate (1940): 10.2%

Farm housing in disrepair (1950): 4.7%

Nonfarm housing in disrepair (1950): 8.7%

Average farmhouse value (1930): $2,401
Average outbuilding value (1930): $2,223

Average farmhouse size (1940): 6.8 rooms
Number of farms (1920): 1,899
Average farm size (1920): 142.5 acres
Sources of settlement: Ohio, Pennsylvania, New York, Sweden, Indiana, Kentucky, and Ireland
_________________________________________________________________________________

Monmouth

Namesake: Monmouth County, New Jersey

Founding: 1831 (platting as Kosciusko); 1841 (post office); 1852 (incorporation)

Population (2020): 8,902

Population (historic): 797 (1850); 4,662 (1870); 5,936 (1890); 9,128 (1910); 8,666 (1930)

Periods of population growth: pre-1850–1910; 1920–1970; 1990s
Pre-1940 residences (estimated): 1,591 (41.8%)
_________________________________________________________________________________

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

Outstanding Buildings

1. Franklin Snapp Farm (c. 1855). 514 Wolf Road. Greenbush. Greek Revival. Razed.
2. Pleasant Green School (1909). 235th Road and 1st Road. Hale. Classical Revival/Romanesque. Razed.
3. Chapman Brooks Farm (c. 1870). 1100 192nd Road. Monmouth. Italianate.
4. George Tucker Farm (1854). 521 85th Road. Roseville. Greek Revival.
5. Hugh Martin House (c. 1860). 901 East Main Street. Sumner. Italianate.

_________________________________________________________________________________