There are 3 US Post Offices in Grant County serving a total of 875 residents equating to 292 residents per post office. It's estimated that approximately 1,397 packages are handled across the 3 county post offices annually. Grant County is a county located in the U.S. state of Nebraska. As of the 2010 census, the population was 614, making it the fourth-least populous county in Nebraska and the ninth-least populous county in the United States. Its county seat is Hyannis. The county was founded in 1887 and named for Ulysses S. Grant, 18th President of the United States. In the Nebraska license plate system, Grant County is represented by the prefix 92 (it had the ninety-second-largest number of vehicles registered in the county when the license plate system was established in 1922)."