Missouri

I

Introduction

Missouri, state in the central United States. Missouri is bordered on the north by Iowa, on the west by Nebraska, Kansas, and Oklahoma, on the south by Arkansas, and on the east by the Mississippi River, which separates it from Tennessee, Kentucky, and Illinois. The name of the state is taken from the Missouri River and is an Algonquian name for a group that lived near the mouth of the river. The state’s most famous city, St. Louis, lies near the convergence of two great inland water routes, the Missouri and the Mississippi rivers. Jefferson City is Missouri’s capital. Kansas City is the largest city.

Located in the geographic heart of the nation, Missouri is one of the foremost agricultural states in the country and is one of the most important manufacturing states in the Midwest. Midwestern in its grain and cornfields, Southern in its cotton fields, Western in its cattle raising, and Eastern in its manufacturing, Missouri is today more than ever the Center State, as it is sometimes known, and a major transportation crossroads.

When it was admitted to the Union as the 24th state on August 10, 1821, Missouri was the nation’s western frontier. Soon, however, it became known as the Gateway to the West, because of the great overland routes that led from Missouri to California and Oregon. Still another nickname was added to the list in 1899, when Congressman Willard D. Vandiver said: “I come from a country that raises corn and cotton and cockleburs and Democrats, and frothy eloquence neither convinces nor satisfies me. I’m from Missouri. You’ve got to show me.” After that, Missouri became known as the Show Me State.

II

Physical Geography

Missouri ranks 21st in size among the 50 states. Its area of 180,533 sq km (69,704 sq mi) includes 2,119 sq km (818 sq mi) of inland water. The state’s distances at their maximum are 587 km (365 mi) from east to west and 513 km (319 mi) from north to south. The mean elevation is about 240 m (about 800 ft).

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A

Natural Regions

Within Missouri are found three of the major physiographic provinces of the United States: the Central Lowland, the Ozark Upland, or Ozark Plateau, and the Gulf Coastal Plain. Each of these physiographic regions and its subdivisions, or sections, has a distinctive combination of topography, soils, and natural vegetation.

A large part of the Central Lowland in Missouri constitutes a section called the Northern Plains, or the Dissected Till Plains. This section occupies almost all of the state north of the Missouri River. The Northern Plains occupy not only northern Missouri but also adjacent portions of Kansas, Nebraska, and Iowa.

The name Dissected Till Plains suggests the origin of this area’s topography. Till plains are gentle plains composed of rock and soil particles and fragments left behind by retreating glaciers. In Missouri, continental glaciers once reached approximately as far south as the Missouri River, which marks the southern edge of the Northern Plains. After they retreated, the glaciers left behind the gentle surface of a till plain. The glaciation of northern Missouri occurred relatively early in the sequence of ice-sheet advances and retreats in North America. Therefore there has been time since glaciation for stream erosion to roughen the original gentle surface of the till plain, and the plain has been dissected, or cut up, by the action of rivers deepening and widening their valleys.

A succession of river valleys bordered by belts of hilly country characterizes the landscape of the Northern Plains. Between these dissected areas lie gently rolling or almost flat areas, which are the remnants of the original till plain. The most level land in the Northern Plains lies in a narrow belt just west of the Mississippi River, where dissection has scarcely begun. Geographers sometimes treat this narrow band of the Central Lowland in eastern Missouri as a separate section, which they call simply the Till Plains. The Till Plains extend eastward into Illinois, where they cover almost the entire state. In Missouri glacial till is usually from 15 to 30 m (50 to 100 ft) thick.

The vegetation prior to European settlement in the Northern Plains consisted of both forest and prairie. The flat floodplains of the rivers and the adjacent belts of hills were the most wooded sections, with oak especially prominent. Areas at some distance from the major streams tended to be covered with prairie grasses interspersed with patches of woodland.

The Osage Plains form another section of Missouri’s Central Lowland. They are often called the Western Plains. This section lies south of the Northern Plains and west of the Ozark Upland. The Osage Plains extend into Kansas, Oklahoma, and Texas.

These plains in southwestern Missouri lay south of the limit of glaciation. Their surface, having received no glacial deposits, reflects the results of erosion of the underlying bedrock and is generally smoother than that of the Northern Plains. Occasional lines of low hills have been formed where a relatively hard layer of rock has resisted erosion and stands out above the rest of the terrain. However, the relief is not impressive in this section of Missouri, nor are the wide shallow valleys cut by the streams.

The Ozark Plateau, or Ozark Upland, occupies most of Missouri south of the Missouri River. It extends into adjacent parts of Arkansas and Oklahoma. The region is also called the Ozark Mountains and sometimes the Ozark Hills or simply the Ozarks.

In overall form the Ozark Upland is an uplifted dome elongated in a southwest-northeast direction. The highest part of the dome in Missouri extends from the southwestern corner of the state northeastward to the Saint Francois Mountains. Large areas along the crest of this dome are between about 375 and 500 m (about 1,200 and 1,600 ft) high. This is not high compared to the Appalachian or Rocky mountains, but it is markedly higher than the surrounding plains. Southeastward from the crest the upland descends fairly steeply, so that it is only about 120 m (about 400 ft) above sea level at its junction with the plains along the Mississippi River. On the northern side of the crest the descent is somewhat more gradual.

Topography in the Ozark Upland does not correspond in any simple way to elevation. As in the Northern Plains, the roughness of the local topography depends on the degree to which streams have cut valleys into the surface, which originally was quite smooth. The most dissected areas show picturesque tangles of deep stream valleys and intervening ridges with steep slopes. They are found near the Current and Black rivers in the southeast, near the White River in the extreme southwest, and near the Osage and Gasconade rivers in central Missouri. In the most deeply dissected areas, principally those on the southern slope of the dome, stream valleys have cut 120 to 210 m (400 to 700 ft) into the upland surface. The surface has been reduced to a series of narrow interstream ridges.

In contrast to the hilly sections, large areas near the top of the dome and some toward its lower edges are relatively undissected. They give the appearance of monotonous, rolling plains. There are deeply entrenched stream valleys in this area, but they are so widely spaced that the casual observer may well be unaware of them. A name often applied to most of this region is the Salem Upland. Part of it, in the southwest, is called the Springfield Plateau. The Springfield Plateau adjoins the Osage Plains. Its surface is almost as gentle as that of the plains, except for occasional river valleys that have made cuts of 60 to 90 m (200 to 300 ft) into the plain.

Most of the Ozark Upland is composed of sedimentary rocks, principally soluble limestones and dolomites, also known as carbonate rocks. Over many thousands of years surface and underground waters have burrowed the uplands into a labyrinth of thousands of caves, springs, and sinkholes. It is known as karst topography. The carbonate rocks cover a hidden core of older, harder igneous rocks. One section of the Ozark Upland, however, differs in character from all other sections. This is the Saint Francois Mountains, at the eastern end of the crest of the dome. Only in these mountains have the sedimentary rocks been sufficiently eroded away so that the underlying igneous rocks are exposed. They form the rounded, knoblike peaks of an old mountain range. The peaks project, in isolation or in clusters, between 230 and 300 m (750 and 1,000 ft) above the surrounding sedimentary basins. One of these knobs, Taum Sauk Mountain, reaches 540 m (1,772 ft) above sea level and is the highest point in Missouri. However, the Saint Francois Mountains area is not generally as rugged as some of the lower, stream-dissected areas.

Before the time of white settlers, forests covered most of the Ozark Upland. These forests consisted of many species of trees, most of which were deciduous hardwoods. Oaks were the most widespread. Mixed with the hardwoods were stands of softwoods, including cedar and pine. They were minor elements in the forest except in the southeast, where pines locally made up a large proportion of the timber. In most areas the forest was relatively open, with abundant grasses growing among the trees, and could be considered a woodland or savanna. In the west the forest was thinner than in the east and was interspersed with large areas of prairie grasses. Almost all of this Ozark forest is gone, but large areas are covered with small second-growth timber and scrub. In national and state forests and other managed lands the forest has returned in dense stands.

A portion of the broad Gulf Coastal Plain that extends across the South from Texas to Florida also extends northward into southeastern Missouri. This section is known as the Mississippi Alluvial Plain or simply as the Southeastern Lowland. It is also called the Bootheel because of its shape.

The Southeastern Lowland is the lowest, flattest, wettest, and most fertile part of Missouri. Its flat surface seems almost featureless to the observer, although isolated ridges stand from 3 to 60 m (10 to 200 ft) above the level plain. This lowland rises less than 120 m (400 ft) above sea level in the north and less than 90 m (300 ft) in the south. The lowest point in Missouri, at 70 m (230 ft), is in the Southeastern Lowland where the Saint Francis River exits the state. Before settlement much of the region was covered with standing water and a dense, swampy forest. It is now largely cleared and artificially drained. The Southeastern Lowland was the focus of some of the highest magnitude earthquakes in U.S. history. In 1811 and 1812 several earthquakes of magnitudes above 8 on the Richter Scale shook the region around New Madrid, causing some lands to sink, others to rise, and affected the course of the Mississippi River. The threat of severe earthquakes continues in the region.

B

Rivers and Lakes

Missouri lies in the drainage basin of the Mississippi River, which forms the state’s eastern boundary. The Missouri River, which forms the state’s northwestern boundary, turns east at Kansas City, crosses the state to a point north of St. Louis, and empties into the Mississippi.

The Northern Plains are drained by the Missouri and by its tributaries the Chariton and Grand rivers. The Osage River flows eastward through the Osage Plains and northern Ozarks and empties into the Missouri River. The Gasconade River and the Meramec River also drain the northern Ozarks. In the southern Ozarks are found the White, Current, Black, and Saint Francis rivers. The Ozarks also contain more than 10,000 freshwater springs. Much of the flow of the rivers enters the channels by springs. The largest is Big Spring near Van Buren.

Maintaining channels of sufficient depth for navigation on Missouri’s two principal rivers has not been easy. The rivers tended to shift their courses, and the volume of water in the riverbeds could vary tremendously from season to season. The gravest danger from these rivers today is that of floods, which destroy farmland both by carrying away topsoil and by depositing unwanted sand. Structures and roads may also be destroyed. Numerous flood control projects in the form of levees have been undertaken on these rivers. Missouri suffered the most from the Great Flood of 1993. Record or near-record flood crests were set along the Mississippi and Missouri rivers. The severity of the flood has prompted national reevaluation of the goals and methods of river management in the United States.

Some of the most ambitious water projects, however, have been undertaken on the smaller Ozark rivers. The damming up of these streams for flood control, electric power generation, and recreation has created Missouri’s major lakes. These lakes have become popular resorts.

The lakes have been created in three general areas. In the northwestern Ozarks are Lake of the Ozarks and Truman Lake on the Osage River, Stockton Lake on the Sac River, and Pomme de Terre Lake, on the Pomme de Terre River. Lake of the Ozarks is large, with about 2,210 km (about 1,375 mi) of twisting shoreline following the valleys of the Osage River and several of its tributaries. In the southwestern corner of Missouri and in adjacent Arkansas a series of dams on the White River have formed Table Rock Lake, Lake Taneycomo, and Bull Shoals Lake. A dam in Arkansas on the North Fork of the White River has formed Norfolk Lake, which extends into Missouri. In the southeastern Ozarks are two smaller reservoirs, Wappapello, on the Saint Francis River, and Clearwater, on the Black River. In northeastern Missouri is Mark Twain Lake on the Salt River, and in northwestern Missouri is Smithville Lake on the Little Platte River. There are many small reservoirs elsewhere in the state. Most of them have been designed for residential developments, municipal water supplies, recreational purposes, and for the preservation of wildfowl.

C

Climate