[3][4] It was named for James Clarke, a Governor of the Iowa Territory.

[5] The first courthouse for Clarke County was a wood frame two–story structure in Osceola.

In 1883 it was replaced with a brick structure on former park area in the town square.

[16] As of the census[17] of 2000, there were 9,133 people, 3,584 households, and 2,498 families residing in the county.

25.90% of all households were made up of individuals, and 13.30% had someone living alone who was 65 years of age or older.

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

The county was reliably Democratic from 1988 to 1996 and Democratic-leaning from 2000 to 2012, but made a 29.5 point swing to back Donald Trump in 2016.