Resident Population in Fergus County, MT was 11.77200 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Fergus County, MT reached a record high of 13.07600 in January of 1980 and a record low of 11.03200 in January of 2019. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Fergus County, MT - last updated from the United States Federal Reserve on May of 2024.