There are 7 US Post Offices in Union County serving a total of 172,725 residents equating to 24,675 residents per post office. It's estimated that approximately 275,688 packages are handled across the 7 county post offices annually. Union County is a county located in the U.S. state of North Carolina. As of the 2010 census, the population was 201,292. Its county seat is Monroe. Union County is included in the Charlotte-Concord-Gastonia, NC-SC Metropolitan Statistical Area."