There are 5 US Post Offices in Harlan County serving a total of 4,062 residents equating to 812 residents per post office. It's estimated that approximately 6,483 packages are handled across the 5 county post offices annually. Harlan County is a county in the U.S. state of Nebraska. As of the 2010 census, the population was 3,423. Its county seat is Alma. The county is home to the Harlan County Reservoir. In the Nebraska license plate system, Harlan County is represented by the prefix 51 (it had the fifty-first-largest number of vehicles registered in the county when the license plate system was established in 1922)."