Resident Population in Mifflin County, PA was 45.92200 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Mifflin County, PA reached a record high of 46.90800 in January of 1980 and a record low of 45.26800 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Mifflin County, PA - last updated from the United States Federal Reserve on May of 2024.