Hall County is a county located in the U.S. state of Nebraska. As of the 2010 census, the population was 58,607, making it the fourth-most populous county in Nebraska. Its county seat is Grand Island. The county was formed in 1858 and named after Augustus Hall, an early judge of this territory.Hall County is part of the Grand Island, NE Metropolitan Statistical Area.In the Nebraska license plate system, Hall County is represented by the prefix 8.