Resident Population in Harmon County, OK was 2.31500 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Harmon County, OK reached a record high of 5.20000 in January of 1976 and a record low of 2.31500 in January of 2024. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Harmon County, OK - last updated from the United States Federal Reserve on April of 2026.