There are 4 US Post Offices in Jefferson County serving a total of 14,836 residents equating to 3,709 residents per post office. It's estimated that approximately 23,680 packages are handled across the 4 county post offices annually. Jefferson County is a county located in the U.S. state of Florida. As of the 2010 census, the population was 14,761. Its county seat is Monticello. Jefferson County is part of the Tallahassee, FL Metropolitan Statistical Area."