It was named after George Clinton, a soldier, politician, Governor of New York, and Vice President of the United States.

Clinton County lies within the till plains physiographic region, and is somewhat flat or gently rolling.

The northern two thirds of the county were covered with an ice sheet during the Wisconsinan Stage, while the southern third was covered by ice sheets during the much older Illinoian Stage.

Because of such a history with ice, glacial features are readily found on the landscape, such as moraines and kames.

The climate of Clinton County can be classified as humid continental.

23.70% of all households were made up of individuals, and 9.90% had someone living alone who was 65 years of age or older.

Since 1856, the only Democrat to win a majority in the county has been Lyndon Johnson in 1964, and he did so by only 432 votes.

The Wilmington Public Library of Clinton County serves the communities of Clinton County from its administrative offices and main library in Wilmington and its Clinton-Massie branch in Clarksville.

Clinton County is home to Cowan Lake State Park, where outdoor recreationalists enjoy fishing, swimming, boating, hiking, bicycling, camping, and wildlife viewing.

Fossil hunting is popular here, in addition to similar activities enjoyed at Cowan Lake.

The city is also the home of the Clinton County Corn Festival.

Several other state and local highways serve the residents of Clinton County.

Clinton Field is a public use airport located four nautical miles (7 km) northwest of the central business district of Wilmington.