Estimate, Median Age by Sex, Total Population (5-year estimate) in Northumberland County, PA was 44.50000 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 Northumberland County, PA reached a record high of 44.50000 in January of 2019 and a record low of 42.70000 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 Northumberland County, PA - last updated from the United States Federal Reserve on May of 2024.