There are 10 US Post Offices in Carter County serving a total of 47,990 residents equating to 4,799 residents per post office. It's estimated that approximately 76,597 packages are handled across the 10 county post offices annually. Carter County is a county located in the U.S. state of Oklahoma. As of the 2010 census, the population was 47,557. Its county seat is Ardmore. The county was named for Captain Ben W. Carter, a Cherokee who lived among the Chickasaw. Carter County is part of the Ardmore, OK Micropolitan Statistical Area. It is also a part of the Texoma region.