Resident Population in Washington County, IA was 22.56000 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Washington County, IA reached a record high of 22.57100 in January of 2022 and a record low of 18.96700 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Washington County, IA - last updated from the United States Federal Reserve on May of 2024.