Resident Population in Lake County, IL was 708.76000 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Lake County, IL reached a record high of 713.25100 in January of 2020 and a record low of 382.63800 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Lake County, IL - last updated from the United States Federal Reserve on May of 2024.