There are 22 US Post Offices in Trumbull County serving a total of 168,419 residents equating to 7,655 residents per post office. It's estimated that approximately 268,816 packages are handled across the 22 county post offices annually. Trumbull County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 210,312. Its county seat is Warren. Trumbull County is part of the Youngstown-Warren-Boardman, OH-PA Metropolitan Statistical Area."