There are 4 US Post Offices in Glacier County serving a total of 13,399 residents equating to 3,350 residents per post office. It's estimated that approximately 21,386 packages are handled across the 4 county post offices annually. Glacier County is located in the U.S. state of Montana. As of the 2010 census, the population was 13,399. The county is located in northwestern Montana between the Great Plains and the Rocky Mountains, known to the Blackfeet as the \"Backbone of the World\". The county is geographically and culturally diverse and includes the Blackfeet Indian Reservation, Glacier National Park, and Lewis and Clark National Forest. The county is bordered by 75 miles of international boundary with two ports of entry (Piegan and Del Bonita) open year-round and one seasonal (Chief Mountain) international border crossing into Alberta, Canada."