Resident Population in Washington County, PA was 210.43400 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Washington County, PA reached a record high of 220.40000 in January of 1978 and a record low of 202.95500 in January of 2002. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Washington County, PA - last updated from the United States Federal Reserve on April of 2026.