There are 6 US Post Offices in Alleghany County serving a total of 11,834 residents equating to 1,972 residents per post office. It's estimated that approximately 18,888 packages are handled across the 6 county post offices annually. Alleghany /\u00e6l\u026a\u02c8\u0261e\u026ani\u02d0/ County is a county located in the U.S. state of North Carolina. As of the 2010 census, the population was 11,155. Its county seat is Sparta."