There are 15 US Post Offices in Warren County serving a total of 39,240 residents equating to 2,616 residents per post office. It's estimated that approximately 62,631 packages are handled across the 15 county post offices annually. Warren County is a county located in the U.S. state of Pennsylvania. As of the 2010 census, the population was 41,815. Its county seat is Warren. The county was formed in 1800 from parts of Allegheny and Lycoming counties; attached to Crawford County until 1805 and then to Venango County until Warren was formally organized in 1819. Warren County makes up the Warren, PA Micropolitan Statistical Area."