(5) The greatest rate of increase in the production of cereals in the United States during the last half century has taken place since 1870. This increase is coincident with three other facts of the utmost importance: (a) The development of the central West, a treeless plain--prior to this period much of the farm land in the United States had been hewn out of the forest, tree by tree; (b) the consolidation of the steam railways into transcontinental lines; and (c) the introduction of the self-binding harvester. Formerly it took at least five men to do what is done today by one man in the harvesting of cereals. ADVANTAGES OF GRAIN FARMING (1) The cost of land excepted, the production of hay and grain requires a small outlay of money. During the past fifty years, many thousands of persons have been able to obtain farms of 160 acres at almost no cost. With a few hundred dollars invested in horses and tools with which to plow the prairie and sow the seed, these fortunate persons have oftentimes been able to pay the whole of their expenses, capital included, from the first crop. The renter who operates a hay and grain farm usually has but a small capital invested in his business. (2) The cereals bring a quick return. Wheat may be sown in September and sold in July; maize may be planted in May and sold in November; oats may be planted in April and sold in August. The short period between seed time and harvest makes the oat crop a favorite one among renters. On the other hand, it takes from three to seven years to produce a marketable horse. It may take ten to fifteen years to begin to realize on an apple orchard. (3) The products are not easily perishable, and hence can be held almost indefinitely. The development of the magnificent elevator system, based upon the principle that the cereals can be handled like water, greatly simplifies the holding and preservation of these staple products. (4) The products are in constant demand, and hence they always find a market. Agricultural commodities may be divided into three classes, depending upon the area which controls the price of the commodity, as follows: (a) price units world-wide, as wheat, cotton, pork; (b) price units local to large districts--products too bulky to ship long distances--such as hay, potatoes and apples; (c) price units local to relatively small areas, such as strawberries and green vegetables. It is obvious that the larger the area which controls the price, the more constant will be the demand. OBJECTIONS TO GRAIN FARMING (1) It exhausts the soil. About two-thirds of the wheat of the United States is consumed outside the county in which it is raised.