Resident Population in Logan County, IL was 27.51800 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Logan County, IL reached a record high of 33.70000 in January of 1971 and a record low of 27.50800 in January of 2023. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Logan County, IL - last updated from the United States Federal Reserve on April of 2026.