Resident Population in Columbia County, WA was 4.05300 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Columbia County, WA reached a record high of 4.50000 in January of 1972 and a record low of 3.89000 in January of 1991. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Columbia County, WA - last updated from the United States Federal Reserve on May of 2024.