There are 4 US Post Offices in Sheridan County serving a total of 5,383 residents equating to 1,346 residents per post office. It's estimated that approximately 8,592 packages are handled across the 4 county post offices annually. Sheridan County is a county located in the U.S. state of Nebraska. As of the 2010 census, the population was 5,469. Its county seat is Rushville. The county was formed in 1885 and named after General Philip H. Sheridan. In the Nebraska license plate system, Sheridan County is represented by the prefix 61 (it had the sixty-first-largest number of vehicles registered in the state when the license plate system was established in 1922)."