Cooper County is located in the central portion of the U.S. state of Missouri. As of the 2020 United States census, the population was 17,103. Its county seat is Boonville. The county was organized December 17, 1818, and named for Sarshell Cooper, a frontier settler who was killed by Native Americans near Arrow Rock in 1814. It is a part of the Columbia, Missouri metropolitan area.

Boonville is a city and the county seat of Cooper County, Missouri, United States. The population was 7,964 at the 2020 census. The city was the site of a skirmish early in the Civil War, on July 17, 1861. Union forces defeated the Missouri State Guard in the first Battle of Boonville. It is part of the Columbia, Missouri metropolitan area.