[3] Adair County has some of the few surviving American Chestnut trees in the United States.

[6] Columbia was chosen as the county seat the following year[6] and the first courthouse was built in 1806.

[6] After the American Civil War, a gang of five men, believed to include Frank and Jesse James from Missouri, robbed the Bank of Columbia of $600 on April 29, 1872.

[6] The Green River is the county's major waterway but is not commercially navigable.

Adair County's agrarian economy produces livestock, dairy products, corn, and tobacco.

[6] Lack of adequate transportation infrastructure hindered the county's prosperity well into the 20th century.

[6] The completion of the east–west Cumberland Parkway in 1973 significantly ameliorated this problem, but since then the county has sought improved road access to the north.

[15] Its schools are:[16] Below is partial listing of known unincorporated communities within Adair County.