There are 7 US Post Offices in Dallas County serving a total of 21,041 residents equating to 3,006 residents per post office. It's estimated that approximately 33,584 packages are handled across the 7 county post offices annually. Dallas County is a county of the U.S. state of Alabama. As of the 2010 census, its population was 43,820. The county seat is Selma. Its name is in honor of United States Secretary of the Treasury Alexander J. Dallas, who served 1814-1816. Dallas County comprises the Selma, AL Micropolitan Statistical Area."