Whitman is an unincorporated community in northeastern Grant County, Nebraska, United States. It lies along Nebraska Highway 2, east of the village of Hyannis, the county seat of Grant County. The University of Nebraska-Lincoln Gudmundsen Sandhills Laboratory lies just north of the community. Although Whitman is unincorporated, it has a post office, …Whitman is an unincorporated community in northeastern Grant County, Nebraska, United States. It lies along Nebraska Highway 2, east of the village of Hyannis, the county seat of Grant County. The University of Nebraska-Lincoln Gudmundsen Sandhills Laboratory lies just north of the community. Although Whitman is unincorporated, it has a post office, with the ZIP code of 69366.