Resident Population in Roosevelt County, MT was 10.31900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Roosevelt County, MT reached a record high of 11.48500 in January of 1985 and a record low of 10.00000 in January of 1973. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Roosevelt County, MT - last updated from the United States Federal Reserve on May of 2024.