Years ago the maps of the United States depicted a vast region west of the Missouri River stippled with dots, which were supposed to imitate sand, and marked with the portentous legend, "Great American Desert." As sturdy pioneers pushed their settlements farther and farther westward, the great American desert began to shrink in size until the roseate descriptions of prospectors and land speculators led one to believe that this whole region needed only a touch of the plough and the harrow to produce the most bountiful crops grown anywhere in the world. Nevertheless, the great domain extending from the twenty-five-hundred-foot level to the crest of the Sierra Nevada Mountains is a region so deficient in rainfall that, for the greater part, ordinary foodstuffs will not grow without irrigation; so farming must be confined mainly to the flood-plains of the rivers. Here and there considerable areas have been made fertile by capturing rivers, damming their streams so as to create great reservoirs, and then measuring out the waters to the farm lands below. The Salt River dam in Arizona, recently completed, will supply water to two thousand square miles, or about twenty-five thousand fifty-acre farms. But in spite of all that man has done and can do to make this region fruitful, not far from half a million square miles will ever remain barren so far as the production of foodstuffs is concerned. Now this whole region, irrigated lands included, does not produce more wealth than the State of New York alone--possibly it does not produce so much. Indirectly, however, it is worth more than two thousand million dollars yearly to the rest of the United States; for it is a great highland whose rims, the Sierra Nevada and the Rocky Mountain ranges, are about two miles high. Now, these lofty ranges wring almost every drop of moisture from the rain-bearing winds of the Pacific Ocean, leaving them too dry to shed any moisture over the eastern half of the United States. Because of this great mountain barrier, the winds that bring rain and bountiful crops to the Mississippi Valley and the Atlantic slope, follow an easier passage, flowing directly from the Gulf of Mexico and the Caribbean Sea. And the copious rains are the chief wealth of this midland region. But the arid western highland possesses a great wealth of its own--a wealth whose influence is world-wide, for it is one of the world's chief storehouses of gold, silver, and copper. Gold and silver are the mediums of commercial transactions, and copper is the chief medium for the transmission of electric power. These metals, therefore, are quite as necessary as are iron and steel. Moreover, this great waste, a seeming incubus on the face of the earth, is each year disclosing more and more of its mineral and agricultural wealth.