Established: Feb. 25, 1885

Elev. at Condon: 2,844'

Area: 1,223 sq. mi.

Average Temp.: January 31.9° July 71.3°

Assessed Value: $997,049,835

Real Market Value: $2,409,860,197

(includes the value of non-taxed properties)

Annual Precipitation: 11.39"

Economy: Agriculture, recreation, environmental services, wind power generation, waste management and waste disposal landfills. Hunting, fishing and tourism are secondary industries. The largest individual employers in the county are Chemical Waste Management of the Northwest and Oregon Waste Systems

Gilliam County was established in 1885 from a portion of Wasco County, and named for Colonel Cornelius Gilliam, a veteran of the Cayuse Indian War. Alkali, now Arlington, was the first county seat. In 1890, voters moved the county seat to Condon, then named “Summit Springs.” A brick courthouse was built in Condon in 1903 which was destroyed by fire in 1954. The present courthouse was built on the same site in 1955.

In the heart of the Columbia Plateau wheat area, Gilliam County has an average farm size of about 4,200 acres, principally raising wheat, barley and beef cattle. 

With elevations of over 3,000 feet near Condon in the south of the county, and 285 feet at Arlington, 38 miles north, the county offers a variety of climates. Two major rivers, the John Day and Columbia, and Interstate 84 traverse the area east to west. Highway 19 connects the county’s major cities north to south and serves as the gateway to the John Day Valley.