The opening of the Middle West and Mississippi Valley brought in a third form of agricultural activity, namely, the production of cereals (such as corn, wheat, oats, rye, and barley) on great tracts of prairie land. This form of agricultural production received a great impetus from the invention of labor-saving machinery, notably the power-reaper. The region of extensive cereal production today includes the Middle West, the Northwest, and the Mississippi Valley, making the richest grain-growing area in the world. ------------------------------------------------------------------------ [Illustration: _LAND REGIONS OF THE UNITED STATES._ ] LAND REGIONS OF THE UNITED STATES The great geographical regions of the United States are indicated by this map. Starting from the East we have the Atlantic Plains and, just behind them, the Eastern Plateaus running north and south. Then come the Appalachian Mountains and the Allegheny Plateaus, followed, still further westward, by the Lake Plains, the Prairie Plains, and the Great Plains. Southward, fringing the Gulf of Mexico, are the Gulf Plains. To the far west are three great land regions, namely, the Rocky Mountain area, the Western Plateaus, and the Pacific Slope. This map should be used in connection with Question 1 (page 354). ------------------------------------------------------------------------ [Sidenote: 4. Cattle raising.] As the frontier rolled westward to the foothills of the Rocky Mountains a fourth type of agriculture—using the term in its wider sense—began to make rapid strides. This was the stock-raising industry, the production of horned cattle and sheep on large tracts of grazing land or ranches. This branch of agricultural activity has made its greatest progress in the Middle Southwest and upon the upland states just east of the Rockies (Montana, Wyoming, etc.). Cattle are raised on the ranches, then shipped to the corn belt where they are fattened before being sent to the abattoirs at St. Louis and Chicago.[156] [Sidenote: Miscellaneous activities.] Other branches of agriculture which have developed largely within the past half century are dairying, market gardening, and fruit growing. These activities are not confined to any one section of the country but to a considerable extent are carried on everywhere. Dairying and market gardening have made most progress within convenient distance of the large cities, although improved transportation facilities in the way of air-cooled and refrigerator cars now permit the shipment of dairy and garden produce over long distances. From all this it can be seen that when one speaks of the interests of agriculture a great many different things are included. The agriculture of the United States is diversified to an extent that is found in no other country.