Resident Population in Richland County, MT was 11.17300 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Richland County, MT reached a record high of 14.20800 in January of 1982 and a record low of 8.93400 in January of 2004. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Richland County, MT - last updated from the United States Federal Reserve on May of 2024.