Resident Population in Winnebago County, IL was 280.92200 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Winnebago County, IL reached a record high of 298.62400 in January of 2008 and a record low of 244.70000 in January of 1972. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Winnebago County, IL - last updated from the United States Federal Reserve on May of 2024.