It was named for Keokuk, the leader of the Sauk tribe, who advocated peace with the white settlers.

The Keokuk County Courthouse was built in 1911, in Sigourney's Public Square Historic District.

[7] The South Branch of the Skunk River drains the topography, flowing eastward through the lower portion of the county.

[15] As of the 2000 United States Census,[16] there were 11,400 people, 4,586 households, and 3,155 families in the county.

27.80% of all households were made up of individuals, and 15.80% had someone living alone who was 65 years of age or older.

For most of its history, Keokuk County has backed Republican Party candidates in presidential elections, with Democratic Party candidates only winning the county in eight presidential elections from 1896 on.

Bill Clinton is the most recent Democratic presidential candidate to win the county (1996), while in 2016 his wife, Hillary Clinton, had the worst performance by a Democrat since 1924, only winning 26.9 percent of the vote.

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