Resident Population in Powder River County, MT was 1.73400 Thous. of Persons in January of 2024, according to the United States Federal Reserve. Historically, Resident Population in Powder River County, MT reached a record high of 2.86200 in January of 1970 and a record low of 1.65700 in January of 2009. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Powder River County, MT - last updated from the United States Federal Reserve on April of 2026.