There are 5 US Post Offices in Phillips County serving a total of 3,957 residents equating to 791 residents per post office. It's estimated that approximately 6,316 packages are handled across the 5 county post offices annually. Phillips County is a county located in the U.S. state of Montana. As of the 2010 census, the population was 4,253. Its county seat is Malta. Before February 5, 1915, Phillips County was part of Blaine County, Montana, and before 1912 both were part of Chouteau County, Montana. It was named in honor of rancher and state senator Benjamin D. Phillips. Its northern boundary is the Canada\u2013United States border with Saskatchewan. The Missouri River defines its southern boundary."