United States Geography

B6

a

Natural Features

Almost all of the Heartland is in the vast central lowland of North America. The land is mostly level with some gently rolling hills. Horizontal sedimentary strata of limestone, sandstone, shale, and dolomite underlie the entire region. The gentle slopes of the region result mainly from glacial action during the Pleistocene Epoch (1.6 million to 10,000 years ago). The flatlands and productive soils were produced during the last Ice Age at the close of the Pleistocene Epoch, as were the Great Lakes, which were formed by glacial scouring and then filled with the melt water of retreating glaciers. Almost all of the surface water in the Heartland drains into the river systems that feed the Mississippi River, and flooding is a natural hazard in the spring. Both the Great Lakes and the Mississippi have long served as vital transportation links that contribute to the economy of the region.

B6

b

Economy

The Heartland has a varied economy that underwent a major transformation late in the 20th century. The region possesses the largest area of highly productive farmland in North America. Industry also plays a major role in the region.

For more than a century, the Heartland supported a thriving center of manufacturing. Since the 1970s, manufacturing has declined. By the end of the 20th century, the economic sector generating the most revenue was the service sector, including commerce and trade. Despite the increase in service industry jobs, the Heartland remains the agricultural and industrial center of the nation.

Both industry and agriculture benefit from an extensive waterway system that includes the Great Lakes and the drainage basins of the Mississippi, Missouri, and Ohio rivers. Navigation is improved by hundreds of canals, locks, and dams, which also improve flood control and generate hydroelectricity. Water transportation moves millions of tons of iron ore and coal to steel mills and other heavy industries. In addition, the relatively level terrain has facilitated construction of a dense network of highways and railroads.

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Agriculture continues to be a major economic force in the region. Rich, deep soils and plentiful rain, complemented by a sunny, hot growing season, give rise to vast and productive croplands specializing in corn, soybeans, alfalfa, hay, and fruits such as apples and cherries. The livestock industry is widespread in the region, with huge feedlot operations supporting cattle production in the west. Hogs, found mainly in Iowa and Illinois, are raised with corn and soybeans. Dairy cattle are found throughout the northern part of the region, particularly in the southern Wisconsin Dairy Belt, famous for its milk, cheese, and butter production.

For more than a century, the U.S. manufacturing belt—including Illinois, Indiana, Ohio, western Pennsylvania, western New York, southern Michigan, and southern Wisconsin—served as one of the great industrial areas of the world. By 1980 the region’s industrial dominance began to wane, challenged by vigorous industrial growth in the South and West and by the decline of manufacturing in favor of service industries. In the last three decades of the 20th century, the region’s share of North American factory production declined significantly.

Although industrial jobs have been leaving the Heartland, the region's industrial districts are still important. Today, auto assembly is important in Cleveland, Ohio. Tire and rubber manufacturing continue in Akron, Ohio. The automobile industry is important in southern Michigan, particularly in Detroit, Flint, Pontiac, Ann Arbor, Ypsilanti, and Lansing, as well as in Toledo, Ohio.

Centers of heavy manufacturing include Chicago, Illinois; Gary, Indiana; and Milwaukee, Wisconsin. The steel industry is still important in the Chicago-Gary region, though much business was lost to competition from Asian steel producers during the closing decades of the 20th century. Indiana and Ohio have diversified industry with factories producing secondary automotive products such as batteries, radios, and automotive transmissions. The middle Ohio River, an 800-km (500-mi) stretch of the Ohio River valley, has been a major center of heavy manufacturing, benefiting from large supplies of industrial coal from western Pennsylvania and West Virginia and from low cost river transportation. Examples of heavy manufacturing in this area include iron and steel, metal products, and fabricated metals and machinery, such as motor vehicle manufacturing and assembly.

In the western section of the Heartland, St. Louis, Missouri, located at the confluence of the Missouri and Mississippi rivers, is a center of diversified industry, with an emphasis on aircraft manufacturing and automotive assembly. The western Heartland also includes major food processing industries in cities such as Des Moines, Iowa; Omaha, Nebraska; Kansas City, Missouri; Council Bluffs, Iowa; and Lincoln, Nebraska.

B6

c

Population

As the largest productive agricultural region and the industrial nucleus of the United States, the Heartland contains the largest population of any region of the nation. Population density varied dramatically throughout the region during the 1990s, from fewer than 4 persons per sq km (about 10 per sq mi) in rural areas to more than 4,642 per sq km (more than 12,024 per sq mi) in the heart of Chicago. The vast majority of the population is concentrated in the many urban areas that developed around manufacturing centers. A decline in manufacturing jobs since the 1970s slowed the rate of expansion in many urban areas, but these cities continued to grow as people chose urban living over rural lifestyles.

Large cities in the region include Chicago, Illinois; Milwaukee, Wisconsin; Detroit, Michigan; St. Louis and Kansas City in Missouri; Indianapolis, Indiana; and Cleveland, Ohio. Chicago is the dominant metropolis. It serves as a wholesale center and transportation hub for the region. St. Louis is a commercial and transportation hub that is the largest urban center between Chicago and the Pacific Coast. Other major cities include Milwaukee, Wisconsin; Detroit, Michigan; and Minneapolis and Saint Paul in Minnesota. Urban expansion continues, although it slowed toward the end of the 20th century, as the region lost population to the South and West.

B

7

The Northern Forests

While the physical characteristics of the Northern Forests region extend through much of central Canada and Alaska, the portion that lies within the contiguous United States is limited to the upper Great Lakes area. This region includes much of northeastern Minnesota as well as northern Wisconsin and Michigan.

The common characteristics that make the Northern Forests a distinctive region are its vast forests and its abundant rivers and lakes. The region’s economy focuses on the export of a few primary products via the shipping routes of the Great Lakes.

B7

a

Natural Features

The Canadian Shield, a vast, gently rolling surface made up of granitic rocks, underlies the eastern two-thirds of the region. During the Pleistocene Epoch, ice sheets scoured the land, remolding the surface and removing most of the existing soil to expose bare rock and rounded hills almost devoid of soil. To the west of the shield is a large, broad lowland that is underlain by softer sedimentary materials, deposited by rivers flowing across the Rocky Mountains and the Canadian Shield.

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