[2] The county was established on January 2, 1835, and named for Governor Isaac Shelby of Kentucky.

[4] As of the census[10] of 2000, there were 6,799 people, 2,745 households, and 1,847 families residing in the county.

30.30% of all households were made up of individuals, and 16.60% had someone living alone who was 65 years of age or older.

The Democratic Party predominantly controls politics at the local level in Shelby County.

Shelby County is a part of Missouri's 5th District in the Missouri House of Representatives and is represented by Lindell F Shumake (R-Hannibal).

Senator Hillary Clinton (D-New York) received more votes, a total of 460, than any candidate from either party in Shelby County during the 2008 presidential primary.