Estimate, Median Age by Sex, Total Population (5-year estimate) in Jefferson County, ID was 31.70000 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 Jefferson County, ID reached a record high of 31.90000 in January of 2020 and a record low of 29.80000 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 Jefferson County, ID - last updated from the United States Federal Reserve on May of 2024.