Resident Population in Buchanan County, MO was 82.95600 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Buchanan County, MO reached a record high of 90.02800 in January of 2009 and a record low of 82.91100 in January of 2022. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Buchanan County, MO - last updated from the United States Federal Reserve on May of 2024.