Estimate, Median Age by Sex, Total Population (5-year estimate) in Lewis and Clark County, MT was 41.20000 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 Lewis and Clark County, MT reached a record high of 41.30000 in January of 2020 and a record low of 40.40000 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 Lewis and Clark County, MT - last updated from the United States Federal Reserve on May of 2024.