Resident Population in Fayette County, IL was 21.16400 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Fayette County, IL reached a record high of 22.44400 in January of 1981 and a record low of 20.63700 in January of 2004. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Fayette County, IL - last updated from the United States Federal Reserve on May of 2024.