Formed on December 11, 1801, a part of Green County was made into Adair County named after military veteran, former general, and former governor John Adair. Columbia was named the city within the following year. Located on the Western Appalachia, Adair County is made of more than 40% made of woodland and timber and is also home to Green River State Park. As of 2018, the county population was listed as Adair County having 19,215 residents which is a slight increase from the start of the decade.