THE NORTH CENTRAL REGION.—This region, which lies west of the Allegheny Plateau and east of the Great Plains, south of the international boundary and north of the Ozark uplift, is the great agricultural, and the second most important manufacturing, area of the United States. Broadly speaking, the land, which rises in all directions from the Mississippi, is flat or undulating, and only in comparatively few places is it mountainous. In the north, in parts of Michigan, Wisconsin, and Minnesota, there are outliers of the Laurentian area which contain much mineral wealth. The greater part of the region was at one time covered by the ice-sheet, and the soil, consisting of the debris of different kinds of rock, is generally fertile, while it is underlain in places by extensive deposits of coal.
The climate is continental in character ; the range between the heat of summer and the cold of winter is considerable ; and pre cipitation decreases from the east toward the west and north-west. Over the greater part of North Dakota the mean temperature for the three coldest months is from 5° F. to 10° F., while in Kansas it is from 29° F. to 33° F. The mean summer temperature varies from 65° F. to 70° F. in the northern states to between 74° F. and 78° F. in the southern. In the extreme east of the region the annual precipitation is between 40 and 45 inches, while along the western boundary it ranges from between 25 and 30 inches in Kansas to between 15 and 20 inches in North Dakota.
Physical features, soil, and climate alike constitute this region the most important in the United States for the production of cereals. The surface of the land offers few obstacles to the use of machinery, the fertility of the soil encourages extensive rather than intensive methods of cultivation, and the temperature and rainfall are sufficient for the growth of wheat throughout the whole region, and for the growth of maize in its southern half.
The North Central States produce about two-thirds of the wheat crop of the country. North Dakota, South Dakota, and Minnesota, whose most fertile parts belong to the bed of the glacial Lake Agassiz, form the chief hard spring wheat region and yield over one-fourth of the United States crop. Further south, in the region
of hard winter wheat, Nebraska, Kansas, and Missouri produce one-fifth of the year's supply, and Indiana, Illinois, and Ohio, which grow semi-hard winter wheat, one-seventh. The development of the spring wheat area within the last thirty years has been largely due to the improvements in flour-milling machinery which have made it possible to remove from the flour of spring wheat all the fine particles of bran, the presence of which had hitherto affected both its colour and quality. On the other hand, there has been a great decrease in the area under wheat in Illinois, Iowa, and Wisconsin, due partly to the increased cultivation of maize in these states, but chiefly to the deterioration of the land as the result of a long succession of wheat crops. Mixed farming is much more generally adopted now, though in the Dakotas wheat is still the prevailing crop.
The yield per acre is small : only in the east has the average for the last ten years exceeded fifteen bushels ; elsewhere it is usually somewhat below that amount. With the favourable conditions of soil and climate which prevail, it is obvious that the future will see a considerable increase in the yield per acre, as increasing demand brings the land under more intensive cultivation.
The manufacture of flour has naturally become an important industry in the North Central Region, which in 1905 produced nearly two-thirds 1 of the American supply. Minnesota is the leading state, and it is followed by Kansas, Missouri, and Illinois. The chief towns engaged in the industry are Minneapolis, which in earlier times derived its power from the Falls of St. Anthony, though much is now obtained from steam ; Milwaukee and Chicago, which have excellent shipping facilities ; and St. Louis, the centre of the winter wheat region, which is able to export both to the Gulf of Mexico and the Atlantic seaboard.