Resident Population in King County, WA was 2271.38000 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in King County, WA reached a record high of 2274.09400 in January of 2020 and a record low of 1138.90000 in January of 1972. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in King County, WA - last updated from the United States Federal Reserve on May of 2024.