There are 31 US Post Offices in Mobile County serving a total of 401,518 residents equating to 12,952 residents per post office. It's estimated that approximately 640,868 packages are handled across the 31 county post offices annually. Mobile County is the second most-populous county in the U.S. state of Alabama. As of the 2010 census, its population was 412,992. Its county seat is Mobile. The county is named in honor of the indigenous Maubila tribe. Mobile County comprises the Mobile, Alabama Metropolitan Statistical Area."