Resident Population in Mason County, WA was 68.38900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Mason County, WA reached a record high of 68.38900 in January of 2023 and a record low of 20.91800 in January of 1970. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Mason County, WA - last updated from the United States Federal Reserve on May of 2024.