Physical Geography

Nebraska occupies part of two major physiographic regions of the United States: the Great Plains and the Central Lowlands.

The Great Plains section is an elevated region of generally flat to gently rolling land occupying the western two-thirds of the state. It increases in height from roughly 1,500 feet (450 m) above sea level in the east to 4,000 to 5,000 feet (1,200 to 1,500 m) in the west. The westernmost part falls within the area commonly called the High Plains. The highest point, 5,426 feet (1,654 m) above sea level, lies in the state's southwestern corner.

Throughout Nebraska's Great Plains, the surface consists mainly of wind-blown loess and material washed from the Rocky Mountains during past geologic times. One of Nebraska's largest and most distinctive features is the Sand Hills, in the west-central part of the state. Here the dominant land-form is sand dunes, covered and held in place by a meager growth of grass. Elsewhere on the plains, particularly in the west, there are steep cliffs, river-cut bluffs, buttes, and badlands.

The Central Lowlands section occupies the eastern third of the state. It is a low-lying, flat to rolling land with a deep mantle of loess and material laid down by glaciers during the last Ice Age. Throughout much of this plain, rivers have carved relatively deep, broad valleys. Elevations range from about 1,500 feet (450 m) in the west to less than 1,000 feet (300 m) in the east. The lowest point, 840 feet (256 m) above sea level, is in the Missouri River valley in the southeastern corner of the state.

As throughout most of the northern Great Plains, drainage is eastward to the Missouri River, which forms Nebraska's eastern border. Within the state the chief river is the Platte, formed by the union of the North Platte and South Platte rivers. It follows an S-shaped course to the Missouri, draining all but the most northern and most southern parts of the state. Among the Platte's principal tributaries are the Loup and Elkhorn rivers. Northern Nebraska is drained primarily by the Niobrara; southern Nebraska, by the Republican and Blue river systems.

Artificial lakes constitute the only sizable bodies of water in the state. Among them are Lewis and Clark Lake, on the Missouri River; Lake McConaughy, on the North Platte; and Harlan County Lake, on the Republican River. Small natural lakes dot the hollows of the Sand Hills. Because so much of the plains readily holds the limited precipitation, Nebraska has one of the largest supplies of groundwater in the United States. Wells supply most of the water used for irrigation in the state.

Nebraska has a climate similar to that of other centrally located states. It is marked by hot summers, cold winters, limited rainfall, low humidity, and wide variations in temperature and precipitation, both seasonally and from year to year. Among the chief influences on the climate are the state's inland location, its varying elevation, and its exposure to storms and differing air masses from the north, south, and west.

Average July temperatures range from 78° F. (26° C.) in the east to 73° F. (23° C.) in the west. This difference stems mainly from increased elevation and cooler nights in the west. Throughout the state, summer daytime temperatures often reach 90° to 100° F. (32° to 38° C.). During January, the coldest month, temperatures average slightly below freezing in the south and slightly above 20° F. (-7° C.) in the north.

Annual precipitation averages about 27 inches (690 mm) in the eastern third of the state, 22 inches (560 mm) in the central third, and less than 18 inches (460 mm) in the western third. Most of it comes as rain during the growing season, especially May, June, and July. Snowfall each year is about 30 inches (760 mm), mainly during late winter and early spring. There are occasional blizzards, tornadoes, hailstorms, and droughts.

Before pioneers arrived, virtually all of Nebraska was virgin grassland. Tall prairie grasses, mainly blue-stem, covered the eastern part of the state. Westward, as precipitation declined, shorter grasses prevailed, Relatively little remains of the original vegetation, largely because of widespread farming and ranching.

Forests cover less than 2 per cent of the land. They occur mainly along major rivers as deciduous, hardwood stands and in some of the higher, rougher parts of the west as coniferous forests, primarily pine. Much of the forested land occurs in the Nebraska National Forest, which consists of several stands in the central and northwestern parts of the state.

Huge herds of bison once roamed Nebraska's plains. Wild animals still found in the state include deer, pronghorn, coyotes, jack-rabbits, skunks, squirrels, and prairie dogs. Nebraska also has a wide variety of freshwater fish, game birds, songbirds, and, seasonally, migratory waterfowl.