There are 10 US Post Offices in Guernsey County serving a total of 36,920 residents equating to 3,692 residents per post office. It's estimated that approximately 58,928 packages are handled across the 10 county post offices annually. Guernsey County is a county located in the U.S. state of Ohio. As of the 2010 census, the population was 40,087. Its county seat is Cambridge, and it is named for the Isle of Guernsey in the English Channel, from which many of the county's early settlers emigrated. Guernsey County comprises the Cambridge, OH Micropolitan Statistical Area, which is also included in the Columbus-Marion-Zanesville, OH Combined Statistical Area."