There are 11 US Post Offices in Berkeley County serving a total of 109,464 residents equating to 9,951 residents per post office. It's estimated that approximately 174,717 packages are handled across the 11 county post offices annually. Berkeley County is a county in the U.S. state of South Carolina. As of the 2010 census, its population was 177,843. Its county seat is Moncks Corner. After two previous incarnations of Berkeley County, the current county was created in 1882. Berkeley County is included in the Charleston-North Charleston, SC Metropolitan Statistical Area."