The Chinook and Clatskanie Native American peoples inhabited this region for centuries prior to the arrival of Robert Gray, captain of the ship Columbia Rediviva, in 1792.

Heavy rains caused the Nehalem River to escape its banks and flood the city of Vernonia and rural areas nearby.

Other elected officials include the sheriff, county clerk, district attorney, treasurer, surveyor, assessor and justice of the peace.

In the 1952 presidential election, Columbia was the only county in Oregon to not back Dwight Eisenhower.

In 2016, Donald Trump won the county with just under fifty percent of the vote, a break with the tradition of choosing Democrats for president.

[26] While Columbia had an 80-year streak of voting for the Democratic nominee, the margin had been as narrow as three percent in 2004[27] and in 1984.

Columbia County is part of Oregon's 1st congressional district, which is represented by Suzanne Bonamici and has a Cook Partisan Voting Index score of D+18.

In the Oregon State Senate, Columbia County is in the 16th District, represented by Republican Suzanne Weber.

The primary industries are wood products and paper manufacturing, trade, construction and horticulture.

[29][30] The extensive stands of old-growth timber, which had attracted many of the early settlers to the area, were completely logged over by the 1950s.

[31] Second-growth timber provides the raw material for local lumber and paper mills.

[33] The five largest private employers in Columbia County are Fred Meyer, Cascade Tissue Group, Wal-Mart, OMIC, USIA,[34] and USG.

[35] Columbia County Rider (CC Rider), a service of the Columbia County Transit Division, provides six intercity bus lines and one "flex route" serving various points of downtown St. Helens and downtown Scappoose.

[38] The transit service is largely funded by grants from the Oregon Department of Transportation and the federal government.

Attempts at making CC Rider a separate transit district and to introduce new taxes to fund it have repeatedly failed since 2015.

[39][40] Single-ride fares range from $2 to $6 per ride, depending on number of zones traveled.