Gilliam County, Oregon

Founding: 1885
Parent counties: Umatilla and Wasco
Namesake: Cornelius Gilliam, Oregon pioneer
Seat: Arlington (1885–1890); Condon (1890–)
Land area: 1,205 square miles
Population (2020): 1,995
Population (historic): 3,600 (1890); 3,701 (1910); 3,467 (1930)
Periods of population growth: pre-1890; 1900–1920; 1950s; 1990s; 2010s
Subdivisions: Three cities
National Register listings: Three
Pre-1940 residences (estimated): 373 (33%)
Pre-1940 housing survival rate: 36.5%

Farm housing in disrepair (1950): 19.4%

Nonfarm housing in disrepair (1950): 11.1%

Average farmhouse value (1930): $1,487
Average outbuilding value (1930): $1,828
Average farmhouse size (1940): 5.1 rooms
Number of farms (1920): 454
Average farm size (1920): 570.5 acres
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Condon

 
Namesake: Harvey Condon, surveyor
Founding: 1883 (platting); 1884 (post office); 1893 (incorporation)
Population (2020): 711
Population (historic): 60 (1890); 1,009 (1910); 940 (1930)
Periods of population growth: 1883–1920; 1940–1960; 1990s; 2010s
Pre-1940 residences (estimated): 198 (43.8%)
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Outstanding Buildings

1. *Silas Rice Log House (1884). 505 North Oregon Street.