Resident Population in Madison County, IL was 262.75200 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Madison County, IL reached a record high of 269.31500 in January of 2010 and a record low of 244.43700 in January of 1982. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Madison County, IL - last updated from the United States Federal Reserve on May of 2024.