Resident Population in Allegheny County, PA was 1224.82500 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Allegheny County, PA reached a record high of 1605.13300 in January of 1970 and a record low of 1215.71600 in January of 2019. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Allegheny County, PA - last updated from the United States Federal Reserve on May of 2024.