what county is columbia mo
Columbia, , MO. Employment. Columbia is Missouriâs 5th largest city, with a population of 89,593, and is the county seat of Boone County. State government is Boone Countyâs largest employer. Boone Countyâs population is projected to increase by. 26.7% by 2025, faster than the 9.2% projected state growth. Total Private 53,419 --.