Resident Population in Fallon County, MT was 2.99400 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Fallon County, MT reached a record high of 4.10000 in January of 1971 and a record low of 2.60900 in January of 2006. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Fallon County, MT - last updated from the United States Federal Reserve on May of 2024.