region of grass-covered, stabilized sand dunes in the High Plains of north-central Nebraska, U.S. Extending 265 miles (425 km) across Nebraska and a portion of southern South Dakota, it covers some 19,300 square miles (50,000 square km). It lies mostly to the north of the Platte and North Platte rivers. The Niobrara River passes through the northern Sand Hills and forms part of the northeastern boundary.

The Sand Hills formed mainly between 8,000 and 5,000 years ago. Wind sculpted the fine grains of primarily quartz sand into dunes (sand dune) as much as 20 miles (32 km) long and 400 feet (120 metres) high, now held in place by grass. The region's climate ranges from semiarid (west) to subhumid (east) and is continuously windy. Precipitation, though low, is quickly absorbed by the permeable soil, becoming part of a vast groundwater reservoir that promotes vegetation growth and supplies streams such as the Snake, Calamus, Dismal, North Loup, and Middle Loup rivers. Frequently the groundwater forms shallow lakes, marshes, or wet meadows in valleys between the dunes. Lakes are especially common in the north and west, varying in size and number based on evaporation rates and rainfall. Wetlands support a wide variety of waterfowl and migratory birds. The area contains a unique mix of northern boreal, western coniferous, and eastern deciduous tree species as well as tallgrass and short-grass prairie. Coyotes, deer, jackrabbits, kangaroo rats, beavers, and prairie dogs are common animals.

The Sand Hills grasslands were fertile bison-hunting grounds for Plains tribes such as the Pawnee, Omaha, Ponca, Cheyenne, and Sioux. Settlers avoided the Sand Hills until the late 1870s, when it became an important cattle-ranching district. Ranching (ranch) remains the basis of the economy, with the majority of the area devoted to rangeland and supporting one-third of the state's beef cattle. Ranches are often thousands of acres in size and operated by the same family for generations. The sparsely populated Sand Hills region is the site of two planted national forests and three national wildlife refuges. Hunting, rodeos, and roundups are popular activities. Arthur Bowring Sandhills Ranch State Historical Park, in the north near Merriman, preserves a working ranch from the early 20th century.