Resident Population in Franklin County, IL was 37.13800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Franklin County, IL reached a record high of 44.08400 in January of 1981 and a record low of 37.13800 in January of 2023. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Franklin County, IL - last updated from the United States Federal Reserve on May of 2024.