There are 2 US Post Offices in Rock County serving a total of 1,519 residents equating to 760 residents per post office. It's estimated that approximately 2,424 packages are handled across the 2 county post offices annually. Rock County is a county located in the U.S. state of Nebraska. As of the 2010 census, the population was 1,526. Its county seat is Bassett. In the Nebraska license plate system, Rock County is represented by the prefix 81 (it had the 81st-largest number of vehicles registered in the county when the license plate system was established in 1922)."