LaSalle County, Illinois

Founding: 1831
Parent counties: Putnam and unorganized territory

Namesake: René-Robert Cavelier, Sieur de La Salle, French explorer
Seat: Ottawa (1831–)

Land area: 1,135 square miles

Population (2020): 109,658

Population (historic): 9,348 (1840); 48,332 (1860); 70,403 (1880); 87,776 (1900); 97,695 (1930)

Periods of population growth: pre-1840–1980; 1990–2010

Subdivisions: Eight cities; 24 villages; two CDPs; 37 townships

Pre-1940 residences (estimated): 14,738 (29.4%)
Pre-1940 housing survival rate: 61%
Pre-1860 housing survival rate (1940): 34.9%

Farm housing in disrepair (1950): 5.8%

Nonfarm housing in disrepair (1950): 4.4%

Average farmhouse value (1930): $2,335
Average outbuilding value (1930): $2,865

Average farmhouse size (1940): 7.3 rooms
Number of farms (1920): 4,213
Average farm size (1920): 143.1 acres
Sources of settlement: New York, Ireland, Germany, Pennsylvania, Ohio, England, Norway, and Massachusetts
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Ottawa

Namesake: The Ottawa people

Founding: 1830 (platting); 1832 (post office); 1853 (incorporation)

Population (2020): 18,840

Population (historic): 7,736 (1870); 9,985 (1890); 9,535 (1910); 15,094 (1930)

Periods of population growth: pre-1870–1900; 1910–1960; 1990–2020
Pre-1940 residences (estimated): 2,627 (29.8%)
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Outstanding Buildings

1. House (c. 1845). 1980 35th Road. Dayton. Greek Revival.
2. Annunciation Catholic Church (1924). 1203 State Route 18. Eagle. Gothic Revival.
3. William Gentleman House (c. 1855). 1830 2703rd Road. Fall River.
4. Herman Knoll Farm (c. 1905). 1895 2703rd Road. Fall River. Classical Revival/Queen Anne.
5. Henry Wollenhaupt Farm (c. 1880). 2294 18th Road. Grand Rapids. Italianate.
6. Francis Bowen Farm (c. 1880). 4002 2750th Road. Mission. Italianate.
7. The Oaks / William Wallace House (1858–1860). 2101 Caton Road. Ottawa. Gothic Revival.
8. Sts. Peter and Paul Catholic Church (1872). 3888 1st Road. Troy Grove.
9. Spring Valley House (c. 1849). 1042 27th Road. Utica. Greek Revival.

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