Resident Population in Shelby County, IL was 20.56800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Shelby County, IL reached a record high of 23.97300 in January of 1981 and a record low of 20.56800 in January of 2023. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Shelby County, IL - last updated from the United States Federal Reserve on May of 2024.