Andrew County is a county located in the northwestern part of the U.S. state of Missouri. As of the 2020 census, the county had a population of 18,135. Its county seat is Savannah. The county was organized January 29, 1841, and named for Andrew Jackson Davis, a lawyer and prominent citizen of St. Louis. Andrew County is part of the St. Joseph, MO–KS Metropolitan Statistical Area, which is included in the Kansas City, MO–KS Combined statistical area.