There are 7 US Post Offices in Cleveland County serving a total of 186,977 residents equating to 26,711 residents per post office. It's estimated that approximately 298,436 packages are handled across the 7 county post offices annually. Cleveland County is a county in the central part of the U.S. state of Oklahoma. The population was 255,755 at the 2010 census, making it the third-most populous county in Oklahoma. Its county seat is Norman. The county was named after U.S. President Grover Cleveland. Cleveland County is part of the Oklahoma City, OK Metropolitan Statistical Area."