The Agricultural Core: The Deep North

United States Geography

 he Agricultural Core is a culture region based on an accumulated mix of habits, attitudes, and reactions to the traditional opportunities for livelihood and contact with other groups within the region. Basically, the Agricultural Core is small-town and rural America specially flavored with the agricultural patterns of this region. The population of the Agricultural Core is politically and socially cautious yet independent, secure in what has proven successful and not strongly exposed to the pressures for change found in major urban centers or in the transition zones between regions. "Middle America" is a popular term applied to the region.

The Agricultural Core population received contributions of foreign-born migrants, most of whom originated in northwestern Europe, until late in the 19th century. Later immigrants, from eastern Europe and Mediterranean countries, found the better agricultural land occupied, and settled in the nearby metropolitan areas of the Manufacturing Core.


The settlers who moved across the Appalachians and onto the eastern interior plains were concerned with survival and pursuit of a livelihood. Except for the resistance of the local American Indian population and the usual vagaries of nature, the environment was supportive. Most of Ohio, Indiana, and lower Michigan was covered by a mixed hardwood forest. The trees encountered indicated to the experienced easterner where the best soils were located. They also provided considerable local fuel and building material. Near the western margin of Indiana and farther into Illinois and southern Wisconsin, the small openings and glades in the forest were larger and more frequent. Except along the rivers and in hillier country, Illinois, Iowa, and parts of southern Minnesota and northern Missouri appeared to be as much open grassland as forest. By the time settlers reached north-central and western Iowa, the dense woodlands had been left kilometers behind.

In general, the presence of trees indicates adequate moisture for crop growth. And except for the northwest corner of the region and a few sections of Michigan and eastern Wisconsin, the entire Agricultural Core receives an average of more than 75 centimeters of precipitation each year. The southern margin of the core can expect in excess of 100 centimeters. More important, most of this precipitation occurs between the end of April and the beginning of November, during the growing season. Also important to plant growth, the variability of this rainfall over a 10-year period is low. Summer rains do often come in the form of intense thundershowers, occasionally accompanied by damaging hail and high winds, but even in this the region's farmers are less likely to be economically crippled than are those located on the open plains.

Like other interior regions of America, the Agricultural Core is characterized by a wide range in its temperatures. The coldest winter temperatures at a given latitude are often as low as those occurring much farther north. Similarly, summer temperatures can be expected to climb as high as those found at more southerly latitudes. At Peoria, Illinois, for example, near the center of the Agricultural Core, the average temperature in January is -4C, while the average in July is 24C.

For the agriculturalist, the high summer temperatures encourage rapid crop growth; for the average nonfarm resident, summer can mean a miserable combination of hot days, warm nights, and high humidity. The Agricultural Core's winters are long, often gray, and uncomfortably cold.

Just as the Agricultural Core's climatic mix is highly appropriate for farming, the region's topographic relief is properly moderate. The landscape is gently rolling with few areas of either very flat or very hilly terrain. The low relief means that a very large proportion of the total area can be used for cultivation, and fields can be as large as practical for good management without a high risk of erosion.

As farm machinery was developed, it could be used throughout the region. The scattered hillocks and stream courses that broke up the unending land swells were obvious locations to maintain woodlot or pasture. The rolling landscape also permitted good soil drainage and, in most cases, restricted swamps to small areas.

The landscape that dominates the Agricultural Core is largely a consequence of the same glaciation that created the harbors of Megalopolis. As the heavy ice mass spread outward from its Canadian Shield center, soft sedimentary hilltops were ground down by the weight and movement of the ice. The debris removed in this way became incorporated in the ice sheet, gradually settling out and partially filling the valleys between the decapitated hills. As the glacier fronts later retreated, long, low hills of this debris remained to offer a few lines of slightly greater relief for the human populations that followed. The tremendous quantity of meltwater released by the glacial retreat eroded several major river outlets, such as the Illinois River west and south from Lake Michigan and the Mohawk-Hudson river valleys east and south from Lake Ontario. The higher surface altitude of the Great Lakes during this period submerged large areas of what is now dry land south of Chicago, south of Saginaw Bay in Michigan, and the Black Swamp lake plain extending from Toledo, Ohio, to Fort Wayne, Indiana.

In north-central Kentucky is a large basin many would argue does not belong within the continent's Agricultural Core. The Bluegrass Basin, or Bluegrass Plains, nevertheless extends the region of low relief and highly productive agriculture into the margins of the Appalachian Plateau. The low, rolling relief of this region is primarily a residual karst terrain, one that has developed over thick limestone bedrock. The limestone is gradually soluble in moving water and permits many major surface features to be worn away. The limestone is also dissolved underground and forms stalactite- and stalagmite-columned caves that can extend for miles. The Mammoth Cave complex southwest of the basin is probably the best known in this region.

The soils of the Agricultural Core are good, often much better than average, but usually not excellent. With the major exception of central Illinois and south-central Wisconsin, soils east of central Iowa are alfisols, formed under conditions of moderate moisture and usually in association with coniferous or mixed forests. Although the thin surface soil is deficient in humus, the soil retains agriculturally important minerals. In general, the soils found throughout the eastern Agricultural Core require only careful plowing, some form of crop rotation, and the application of agricultural lime to remain productive.

Western soils within the region and those throughout much of Illinois are mollisols, among the most fertile of all soils and naturally suited to grain production. These soils were formed under grasses rather than under forest cover. They range in color from dark brown to almost black, indicating a very high organic content. They also tend to be rather deep, with the surface horizon between 50 and 150 centimeters.

The major soil exceptions to these two broad categories are the alluvial soils, found within the main river valleys and former lake beds, and the swamp soils. Both types of soil are capable of high fertility but often require special treatment.

The natural environment of the Agricultural Core provided highly beneficial transportation opportunities. Even prior to the railroads and to extensive development of the road network, the river and lake connections within the region permitted easy and inexpensive shipment of goods to the eastern seaboard population centers and to the main international trade ports.

Movement of settlers into the region was earliest along the larger waterways. The southern Great Lakes, the Ohio River, the Illinois, Wabash, and Wisconsin Rivers to the east of the Mississippi, and the Missouri River westward to Kansas City all provided major routes of entry for settlers and major routes for marketing their produce. The eastern Great Lakes offered more direct shipment through the Mohawk-Hudson routeway to New York City. The entire interior river network funneled into the Mississippi River system and was navigable by small boats and barges with very few interruptions throughout.

The city of Detroit, Michigan, grew as a military control point and focus for farm products. This city, whose name means "the narrows" in French, is located at the best crossing point between Ontario, Canada, and Michigan and is also near the entry of the northern lakes into Lake Erie. The southern Michigan hinterland was not as rich agriculturally as that of northern Ohio, however, and Cleveland, Ohio, remained more populous until after 1910, when mass-produced automobile industries transformed Detroit's economic structure.

Located at the Great Bend of the Ohio River, Cincinnati, Ohio, became the main collecting and shipping center for agricultural products from the southeastern portions of the Agricultural Core as early as 1820. Kansas City, Missouri, at the junction of the Kansas and Missouri Rivers, also experienced early urban growth by handling large quantities of agricultural products in river transit. Chicago's location, near the southernmost end of Lake Michigan and only a short land distance from the upper Illinois River, also was beneficial to rapid growth. The transshipment opportunities provided by this site were supplemented by extensive canalization projects and by land connections built west and south across the rich Agricultural Core and, later, eastward directly to the growing cities of Megalopolis.


As the settlement frontier moved westward across the Agricultural Core during the early 19th century, it was accompanied by a wave of wheat production for eastern markets. The bulk of raw wheat was not a great problem for shippers while water transport was continuous, but flour milling soon became established at the points of embarkation (such as Cincinnati on the Ohio River) or at sites at which the grain was to change from one transport mode to another (such as Buffalo, New York, at the lake terminus of the Erie Canal). Continuous wheat farming was hard on the region's soils, however, and primary zones of production moved westward with the expanding line of settlement.

For farmers who remained behind, the next best agricultural product was meat from domestic livestock. Both cattle and hogs were raised. So economically reliable was feed grain and livestock farming that it quickly supplanted wheat production as the dominant farming system throughout the Agricultural Core.

Corn (maize) was the grain that best met the combination of environmental requirements and high economic return. Well adapted to a humid summer climate, corn thrives during the region's long hot days and warm nights. Also, yields are high since plants can be grown close together, and each plant produces two or more ears of grain. Furthermore, the large quantity of vegetative matter produced by each plant can be used as feed with appropriate supplements and cutting.

The mixed farming operation of crop-livestock production has provided farmers with economic security beyond that found in any other U.S. agricultural region.

A distinctive characteristic of the central Agricultural Core landscape is a semiregular rectangular field pattern. The original 13 U.S. states had developed their internal boundaries in an unsystematic manner, using the metes and bounds system of lot designation that relied on visible landscape features, compass directions, and linear measurement. The irregularly shaped results were often subject to confused interpretation and litigation. Through the Ordinance of 1785, the land north of the Ohio River and west of Pennsylvania, known as the Northwest Territory, was delimited according to the regular rectangular township and range survey before it was opened to settlement. The irresistible logic of this system remains visible in the predominantly rectangular road network of most of the United States between the Appalachians and the Rockies.

While the land survey system and the ecological and economic realities of the Agricultural Core produced an inevitable homogeneity to the landscape, there are portions of the Agricultural Core that lie beyond the "Corn Belt." In Wisconsin and central Minnesota, north of the centers of grain production where the climate prevented feed grain maturation, farmers chose dairy farming as an economic substitute. Corn in silage, other grains such as oats and barley, and abundant hay crops provided excellent support for large dairy herds. When the supply of fresh milk exceeded even the large demand of the nearby cities, it was converted into butter and cheese for more leisurely shipment to more distant markets. Wisconsin continues to produce a large proportion of America's surplus milk and approximately half of its cheese output.

Another distinctive extension of the agricultural core's boundaries occurs around the western Great Lakes, where fruit production is possible in a narrow band along the Lake Michigan shores of Wisconsin and Michigan. The moderating influence of the lake retards fruit tree blossoming in the spring, usually until after the last frost, and also retards the arrival of the first killing frost in the fall. Sour cherry, apple, and, to a lesser extent, grape production are all important. A similar effect is found along the southern shore of Lake Erie, especially the few lakeshore counties in Pennsylvania and western New York, where grape production has been significant for more than a century.


The Agricultural Core was pretty well settled by 1890, and the corn-livestock farming system that worked well in southern Ohio was carried west to the edge of the Great Plains with only local adjustments. Early technological improvements such as the reaper (1831), the steel plow (1837), and other devices suited to the region's chief economic activity tended to ensure the system's success. More recent changes, however, have stimulated modifications to the traditional geographic patterns.

One of the more subtle changes in Corn Belt patterns lies in the rise of the importance of soybeans since the 1950s. As late as 1925, less than 200,000 hectares of soybeans were harvested in the United States. By 1949, soybean acreage had increased to about 4.5 million hectares, and during the next 20 years, it exploded to 16.1 million hectares; plantings in the Agricultural Core exceeded 10 million hectares. Nationwide today, some 20 million hectares are planted in soybeans.

The reasons for the tremendous increase in soybean production are several. First, as a legume, soybeans act as a soil reconditioner by increasing the nitrogen content of the soil in which they are grown. Second, soybeans generally may be grown throughout most of the eastern United States, and even in areas receiving less than 50 centimeters of rainfall if irrigation is feasible. Third, the bean itself can be eaten directly or milled to produce an edible vegetable oil and a meal low in fat but very high in protein. The meal has been used primarily as a livestock feed supplement, but an increasing amount has entered human consumption patterns. And fourth, the world food and feed situation maintained export demand for soybeans at high levels. This has kept prices relatively stable, an encouraging condition to farmers.

This combination of advantages has concentrated a great amount of soybean production in the Agricultural Core. The traditional three- and four-year rotations gradually gave way to a two-year corn-soybean rotation. In some cases within southern portions of the core, early maturing varieties of soybeans can be planted in the late spring after a harvest of winter wheat, giving the farmer three crops (corn, wheat, soybeans) every two years without significant loss of productivity in any year.

A more complex set of changes in Agricultural Core geography is built on new levels of mechanization and alterations in average farm size. The original land survey in the region set the minimum farm size that could be purchased at 64.75 hectares, and then at half or one quarter that amount at various times. After the initial purchase, of course, parcels of land could be broken up and sold in even smaller lots or added to previously established farms.

By 1900, farm size in the Agricultural Core states showed marked variation: about one-third of the farms were of 73 to 202 hectares, another third were of 40 to 72 hectares, and most of the remainder were smaller than 40 hectares. The amount of land in farms smaller than 73 hectares began to decline after 1935. By 1964, more than 50 percent of the farmland in these states was in farms larger than 105 hectares; fully one hectare in five was located on a farm larger than 202 hectares, a trend that has continued.

The reasons for these changes in farm size are economic and related to mechanization of operations. Agricultural Core farmers traditionally have taken advantage of mechanical innovations to increase their output per work-hour. The large fields and gentle terrain in this region permitted early and continuing use of farm machinery that would have been impossible on smaller farms and erosion-prone hill farms.

A labor shortage during the early 1940s as the result of World War II accelerated the mechanization process, and innovations became oriented increasingly toward large-scale operations. Two- and four-row equipment gave way to six- and eight-row equipment. Storage and shipment operations also became mechanized and more and more attuned to the requirements of large-volume producers.

Accompanying the changes in farm size, the amount of land farmed in the region declined gradually. The proportion of land in farms was above 80 percent across much of the region in 1987, with most of Iowa and Illinois still showing rates above 90 percent. Even so, the overwhelming number of counties in the Agricultural Core had experienced a reduction in land in farms across the previous two decades.

While still dominant, the fully owned, individually operated family farm is disappearing rapidly from the Agricultural Core states. This decline is associated with the demands of increased farm efficiency. Personal effort and individual integrity still contribute to a farm's success, but the factor of scale is increasingly critical.

As the need for more land per operation increased, some farmers found it feasible to rent or lease additional land rather than purchase it outright. Other farm operators may be full tenants, choosing to work for the landowner through one of several arrangements. In addition, about one-third of those renting farmland lease it from a relative, often as a means of transferring the land from one generation to another.

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Source: U.S. Department of State