Columbia County, Washington

Columbia County
County
Columbia County Courthouse in Dayton
Seal
Location within the U.S. state of Washington
Washington's location within the U.S.
Coordinates: 46°18′N 117°55′W / 46.3°N 117.92°W / 46.3; -117.92
Country	United States
State	Washington
Founded	November 11, 1875
Named for	Columbia River
Seat	Dayton
Largest city	Dayton
Area
• Total	873 sq mi (2,260 km2)
• Land	869 sq mi (2,250 km2)
• Water	4.9 sq mi (13 km2)  0.6%
Population  (2020)
• Total	3,952
• Estimate  (2022)	4,026
• Density	4.6/sq mi (1.8/km2)
Time zone	UTC−8 (Pacific)
• Summer (DST)	UTC−7 (PDT)
Congressional district	5th
Website	www.columbiaco.com

Columbia County is a county located in the U.S. state of Washington. As of the 2020 census, the population was 3,952,^[1] making it the second-least populous county in Washington. The county seat and largest city is Dayton. The county was created out of Walla Walla County on November 11, 1875,^[2] and is named after the Columbia River (which does not flow through the county). Columbia County is included in the Walla Walla, WA Metropolitan Statistical Area.