Resident Population in Buchanan County, IA was 20.69100 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Buchanan County, IA reached a record high of 23.20000 in January of 1979 and a record low of 20.60600 in January of 2020. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Buchanan County, IA - last updated from the United States Federal Reserve on May of 2024.