Resident Population in Randolph County, IL was 29.90300 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Randolph County, IL reached a record high of 35.82500 in January of 1982 and a record low of 29.90300 in January of 2024. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Randolph County, IL - last updated from the United States Federal Reserve on April of 2026.