There are 47 US Post Offices in Jefferson County serving a total of 597,036 residents equating to 12,703 residents per post office. It's estimated that approximately 952,936 packages are handled across the 47 county post offices annually. Jefferson County is the most populous county in the state of Alabama, in the United States. As of the 2010 census, the population was 658,466. Its county seat is Birmingham, which is also the most populous city in the state. Jefferson County is included in the Birmingham-Hoover, AL Metropolitan Statistical Area."