Resident Population in Decatur County, IN was 26.39900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Decatur County, IN reached a record high of 26.68500 in January of 2018 and a record low of 22.73800 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Decatur County, IN - last updated from the United States Federal Reserve on May of 2024.