Montgomery County, Illinois

Founding: 1821
Parent counties: Bond and Madison

Namesake: Richard Montgomery, Continental Army general
Seat: Hamilton (1821–1823); Hillsboro (1823–)

Land area: 704 square miles

Population (2020): 28,020

Population (historic): 2,953 (1830); 13,979 (1860); 28,078 (1880); 30,836 (1900); 35,278 (1930)

Periods of population growth: pre-1830–1920; 1970s

Subdivisions: Five cities; 15 villages; 18 townships

National Register listings: 13

Pre-1940 residences (estimated): 3,283 (25%)
Pre-1940 housing survival rate: 45.1%
Pre-1860 housing survival rate (1940): 7.7%

Farm housing in disrepair (1950): 3.9%

Nonfarm housing in disrepair (1950): 8.5%

Average farmhouse value (1930): $1,313
Average outbuilding value (1930): $1,083

Average farmhouse size (1940): 5.9 rooms
Number of farms (1920): 3,037
Average farm size (1920): 117.8 acres
Sources of settlement: Ohio, Germany, Kentucky, Pennsylvania, Missouri, North Carolina, Tennessee, and Ireland
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Hillsboro

Namesake: A descriptive name

Founding: 1823 (platting); 1823 (post office); 1855 (incorporation)

Population (2020): 5,902

Population (historic): 853 (1860); 1,803 (1880); 1,937 (1900); 4,435 (1930)

Periods of population growth: pre-1860; 1900–1920; 1930s; 1950–1980; 2000s
Pre-1940 residences (estimated): 385 (21.8%)
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Outstanding Buildings

1. *Lewis Thomas Farm (1863–1865/1888). 34378 East Frontage Road. Bois d'Arc. Romanesque/Classical Revival.
2. Charles Jenkins House (c. 1865). 9032 State Route 127. Butler Grove. Italianate.
3. *Benjamin Ware House (c. 1830). 9138 Ware's Grove Road. Butler Grove. Razed.
4. Amos Sawyer House (c. 1875). 9250 State Route 127. Hillsboro. Italianate.