Resident Population in Phillips County, MT was 4.24900 Thous. of Persons in January of 2023, according to the United States Federal Reserve. Historically, Resident Population in Phillips County, MT reached a record high of 5.65300 in January of 1984 and a record low of 3.88100 in January of 2008. Trading Economics provides the current actual value, an historical data chart and related indicators for Resident Population in Phillips County, MT - last updated from the United States Federal Reserve on May of 2024.