Resident Population in Armstrong County, PA was 63.67900 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Armstrong County, PA reached a record high of 78.30000 in January of 1978 and a record low of 63.67900 in January of 2024. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Armstrong County, PA - last updated from the United States Federal Reserve on April of 2026.