[3] Woodbury County is included in the Sioux City metropolitan area.

[4] Originally established in 1851 as Wahkaw County, the Iowa Legislature in 1853 changed the name to Woodbury County in honor of Levi Woodbury (1789–1851), a senator and governor of New Hampshire who served as a Supreme Court justice from 1844 until his death.

The Winnebago Tribe of Nebraska (Ho-Chunk) owns reservation land in Woodbury County.

For much of the second half of the 20th century, Woodbury County tilted Republican, albeit not as overwhelmingly as most of western Iowa.

This was the only county in Iowa that Barack Obama won in 2012 that he failed to carry in 2008.

However, in 2016, Woodbury County swung over dramatically to Donald Trump, who carried it by a 19 percent margin, the largest margin of victory since Lyndon Johnson's landslide election in 1964.

The population ranking of the following table is based on the 2020 census of Woodbury County.