There are 5 US Post Offices in Montgomery County serving a total of 9,022 residents equating to 1,804 residents per post office. It's estimated that approximately 14,400 packages are handled across the 5 county post offices annually. Montgomery County is a county in the U.S. state of Georgia. As of the 2010 census, the population was 9,123. The county seat is Mount Vernon. Montgomery County is part of the Vidalia, GA Micropolitan Statistical Area.