Resident Population in Multnomah County, OR was 789.69800 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Multnomah County, OR reached a record high of 816.46700 in January of 2020 and a record low of 547.40000 in January of 1975. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Multnomah County, OR - last updated from the United States Federal Reserve on May of 2024.