Nebraska

I

Introduction

Nebraska, state in the West North Central United States. Nebraska is bounded by South Dakota on the north, Kansas on the south, the Missouri River and the states of Iowa and Missouri on the east, and Wyoming and Colorado on the west. From the eastern boundary of Nebraska many explorers, fur traders, and adventurers started their trek across the plains and the Rocky Mountains to the Pacific Coast. Later, settlers moved into the area, seeking inexpensive or free farmland or better opportunities in a growing region. The first land claim under the Homestead Act of 1862 was made in Nebraska (see Homestead Laws), and the eastern terminus of the first transcontinental railroad was Omaha. Nebraska entered the Union on March 1, 1867, as the 37th state. Lincoln is the state capital. Omaha is the largest city.

Midway between the Atlantic and Pacific oceans, Nebraska is a land of transition. Climate, soils, vegetation, and landforms change considerably across the state. The large urban centers of the eastern part of the state give way to small rural communities farther west, where there are large wheat fields and vast expanses of grazing land. Gently rolling hills and forested valleys in the east contrast sharply with the treeless plains and intermittent streams farther west. The Platte River and its tributaries drain most of the state, and the Platte’s broad valley serves as a transportation corridor linking cities with farms and west with east. The river has also indirectly given the state its name, because Nebrathka, meaning flat water, was the Oto name for the Platte River. Nebraska is called the Cornhusker State in reference to its primary agricultural crop.

II

Physical Geography

Nebraska ranks 16th among the states in area, covering 200,346 sq km (77,354 sq mi), including 1,246 sq km (481 sq mi) of inland waters. From east to west, in a line extending from Omaha to the western boundary of its Panhandle, Nebraska measures 687 km (426 mi). The distance from north to south is 333 km (207 mi).

With the exception of the Panhandle to the west, the state is rectangular. It slopes gently to the southeast and elevation increases at an average rate of 2 meters per kilometer (10 feet per mile) from the Missouri River to Nebraska’s western boundary. The lowest elevation, 256 m (840 ft), is along the Missouri River in the southeast, and the highest point, 1,653 m (5,424 ft), is in the Panhandle in southwestern Kimball County. The mean elevation is about 790 m (2,600 ft). Although Nebraska is considered a plains state, there is considerable local relief.

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A

Natural Regions

Two major physiographic divisions, or natural regions, of the United States are represented in Nebraska. They are the Central Lowland and the Great Plains, both of which are subdivisions of the Interior Plains. The eastern fifth of Nebraska is in the Central Lowland, and the remainder of the state forms part of the Great Plains. The Dissected Till Plains of the Central Lowland, which average about 110 to 130 km (about 70 to 80 mi) in width, parallel the Missouri River. This area was blanketed by ice during the early ice ages several hundred thousand years ago. Later it was covered by various thicknesses of loess, or wind-deposited material, and roughened by erosion. The hills of loess-covered glacial deposits are severely dissected, or eroded, by rivers enlarging their valleys near the Missouri River. This dissection has created bluffs that are visible along much of the river.

The Great Plains natural region covers about four-fifths of the state. This region is composed of four distinct areas: the High Plains, the Sand Hills, the Loess Hills and Canyons, and the Loess Plains.

The High Plains in western Nebraska consist of a large expanse of high flat tableland with some rough broken areas. In many areas the soil and mantle are thin and the bedrock is exposed. A rather prominent feature of the landscape in this region is the Pine Ridge Escarpment, a cliff of 300 m (1,000 ft) in elevation. The Sand Hills in central and north central Nebraska consist of grass-covered sand dunes. This region makes up about one-quarter of the state. The sand dunes have been completely grassed over, except for occasional blowouts, which are areas of exposed sand that may cover more than a hectare. Throughout the region there is little variation in composition or in texture of the soil. The Sand Hills are extremely porous, and there is little surface runoff. Most streams in the Sand Hills are fed by springs or artesian wells and have little seasonal fluctuation. The underlying rock strata hold large amounts of usable water, and wells may be dug successfully anywhere within the Sand Hills.

The central and southwestern parts of the Great Plains in Nebraska are made up of loess hills and canyons. Most of south central Nebraska is composed of a slightly dissected loess plain. Most of the southeastern half of the state is capped by loess, ranging in depth from about 1 to more than 90 m (about 3 to more than 300 ft). The thickest deposits are found in central Nebraska, from 60 to 160 km (40 to 100 mi) north of the Kansas border. The loess is windblown unstratified material that often stands nearly vertical in cliffs or road cuts. Soils develop rapidly on loess and are among the most productive in the world.

B

Rivers, Lakes, and Irrigation

Nebraska has one of the best supplies of surface and underground water in the nation. All of its rivers and streams eventually drain into the Missouri River, flowing in an easterly and southeasterly direction. The state’s principal river, the Platte, is formed by the confluence of the North Platte and South Platte rivers, both of which rise in the Rocky Mountains. The Platte River flows through central Nebraska to the Missouri River. The Sand Hills are drained by the Niobrara, Elkhorn, and Loup rivers. The Republican and Big Blue rivers drain the southern part of the state, flowing south into Kansas, where they enter the Kansas River. While there are no large natural lakes in the state, hundreds of small natural lakes are found in the Sand Hills.

Nebraska depends on irrigation for a substantial part of its crop production, and 34 percent of all cropland is irrigated. Much of the irrigated land is in the broad valley of the Platte. Because of the abundant surface and underground water supplies, the valley has been given the nickname “Irrigation Way.”

One of the first United States Bureau of Reclamation projects, the North Platte Project, was built in Nebraska and Wyoming. Water impounded and stored in Wyoming is used for irrigation in southeastern Wyoming and Scotts Bluff and Morrill counties in Nebraska.

A large privately financed irrigation project, the Tri-County Project, uses Platte River water. The state’s largest dam, Kingsley Dam, and largest reservoir, Lake McConaughy, are parts of the Tri-County Project. Three other reservoirs, Lewis and Clark Lake, Harlan County Lake, and Swanson Lake, each have an immense storage capacity. Other major reservoirs in Nebraska include Harry Strunk Lake, Hugh Butler Lake, Enders Reservoir, and Sherman Reservoir.

Nearly four-fifths of the irrigated land in Nebraska, however, uses groundwater pumped from deep wells, rather than surface water supplied from reservoirs. Nebraska possesses enormous groundwater reserves. The Ogallala aquifer, an underground-water bearing layer stretching south as far as Texas, lies under much of central Nebraska. Well irrigation first became important in the late 1930s, but the number of wells increased sharply in the 1950s and 1970s. In the mid-1990s there were more than 60,000 irrigation wells in the state, with the greatest concentrations found in the central and lower Platte valleys, in south central and southwestern Nebraska, and in much of the north central part of the state. The growth in irrigation has put pressure on groundwater supplies and has led to declining water tables in some areas, particularly in the Big Blue River basin and in the southwestern counties. When water tables decline quite rapidly, various restrictions may be put into place by natural resource districts to limit the rate of pumping for irrigation.

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