[3] The county was organized January 2, 1833, and named for Governor DeWitt Clinton of New York.

[6] As of the census[12] of 2017, there were 20,554[13] people, 8,990[13] households, and 8,299[13] families residing in the county.

There were 7,877 housing units at an average density of 19 per square mile (7.3/km2).

22.00% of all households were made up of individuals, and 10.50% had someone living alone who was 65 years of age or older.

Clinton County is split into two Missouri House of Representatives District numbers 8 & 9.