Estimate, Median Age by Sex, Total Population (5-year estimate) in Cass County, IL was 38.80000 Years of Age in January of 2022, according to the United States Federal Reserve. Historically, Estimate, Median Age by Sex, Total Population (5-year estimate) in Cass County, IL reached a record high of 40.20000 in January of 2017 and a record low of 37.50000 in January of 2009. Trading Economics provides the current actual value, an historical data chart and related indicators for Estimate, Median Age by Sex, Total Population (5-year estimate) in Cass County, IL - last updated from the United States Federal Reserve on May of 2024.