The Sand Hills, often written Sandhills, is a region of mixed-grass prairie

Prairie

Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...

 on grass-stabilized sand dunes in north-central Nebraska

Nebraska

Nebraska is a state on the Great Plains of the Midwestern United States. The state's capital is Lincoln and its largest city is Omaha, on the Missouri River....

, covering just over one quarter of the state. The region is variously defined by different organizations, so its size is indicated as 19,600 mi² (50,760 km²) or 23,600 mi² (61,100 km²).
Dunes in the Sand Hills may exceed 330 ft (100 m) in height.