There are 13 US Post Offices in Blair County serving a total of 99,897 residents equating to 7,684 residents per post office. It's estimated that approximately 159,447 packages are handled across the 13 county post offices annually. Blair County is a county located in the U.S. state of Pennsylvania. As of the 2010 census, the population was 127,089. Its county seat is Hollidaysburg. The county was created on February 26, 1846, from parts of Huntingdon and Bedford Counties. Blair County comprises the Altoona, PA Metropolitan Statistical Area."