Resident Population in Putnam County, IL was 5.56100 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Putnam County, IL reached a record high of 6.19300 in January of 1981 and a record low of 5.00000 in January of 1971. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Putnam County, IL - last updated from the United States Federal Reserve on May of 2024.