With the advent of the railroads the modern conquest of the desert began. It was first awakened from its centuries of lethargy by the whistle of the locomotive in the eighties. In the Great American Desert in the United States and Mexico there are now more than 9000 miles of railway. But for the railroad the Great Ameri can Desert would to-day be as unproductive as the Sahara, and still populated, like the Sahara, by people who exist without division of labor, the use of mechanical appliances or extra-terri torial commerce. The first railways to be con structed were designed merely as highways be tween the Atlantic and Pacific seaboards. No thought of revenue from a desert itself was anticipated. Next came a great longitudinal line following the ancient trails of the Aztec from Mexico to Santa Fe. Mining and popu lation soon followed these trunk lines, which are now extending out even into the utmost recesses of the desert. From the Pecos in Texas to California, a distance of 1,500 miles, the route of the Southern Pacific followed a belt of country devoid of water except occasionally in the Rio Grande. Not a herd of cattle, a mod ern house, a farm or a mine existed along this desert stretch. Nor would they exist to-day had it not been for the construction of this railway. Now its course is marked by many prosperous embryo cities and villages.
Notwithstanding the apparent scarcity of water, one of the most remarkable features of the American Desert is that water has been secured, often in apparently impossible places, and in quantities which have made possible the existence of cities and industries. Like the des erts of the Sahara and Asia, those of America have a supply of underground water; there is hardly a desert in which the experiment has been tried where waters have not been found within 2,000 feet of the surface. Though not often sufficient for agriculture, enough has usually been found to afford a supply for cat tle, railroads and mines.
Underground water has usually first been found by the railway companies. When the track was first pushed across the desert, water was brought from the rear in tank cars; but when the track was completed water was bored for in the desert itself. The engineers have had at command a mechanical appliance second only in importance to the locomotive, and one which in the desert usually goes side by side with it. This is the mechanical drill. At great expense they bored in many places. The existence of underground water beneath any particular area having once been demonstrated by the railroad company, individuals, of course, usually repeated the experiment. Three notable triumphs of the mechanical drill over nature are the flowing wells of the Salton Desert, the flowing well at Benson and a supply of 700,000 gallons a day from the deep wells on the Mesa at El Paso.
Each of these supplies of water was obtained from the localities which superficially were hopelessly dry.
Several of the largest mines in the desert de pend almost entirely upon the water trans ported on cars. The Copper Queen runs its vast smelters and machinery chiefly by water thus obtained, while the famous Sierra Mojada, of Coahuila, with its population of 5,000 people, has not a drop of water except that brought in tanks a distance of 125 miles. Yet these two mines annually return millions of profit.
But the sterile and hopeless-looking soil of the desert, when artificially watered, is appar ently more fertile than where rainfall is abun dant. There is no nobler spectacle than a dreary waste converted into an emerald oasis by water artificially applied, and in the desert may be seen some of the most profitable and skilful agriculture in the world. The wheat fields of Utah and Sonora, the great cotton farms of Coahuila, the alfalfa valleys of the Rio Grande and the orchards of California are all inspiring examples. The transformation made in the desert where irrigation has been possible is marvelous, and in one instance — in southern California — has resulted in the de velopment of communities of great wealth and culture, where the ideals of perfect conditions for existence are as nearly attained as possible.
A word of caution must be written, however, against an overestimate of the agricultural ca pacities of the desert. It is necessary artificially to collect the precipitation over large areas, and to concentrate it upon smaller areas by impounds and canals. In this manner at least 25 acres must be set aside as unproductive catchment areas for every one that may be cul tivated. All rain water that falls upon the desert or upon its neighboring mountain, if it could be protected and carefully preserved, would not irrigate 5 per cent of the great des ert area. The efficiency of the rain of the Great Desert region for agricultural purposes is still further diminished owing to the season in which it falls — June to October — too late for the growing crops, the planting and growing months of spring and early summer being dry. From practical standpoint it is doubtful if even 1 per cent of the vast area can ever be profitably tilled by irrigation. The underground water supply, too, is entirely insufficient for extensive agricultural uses, even when it is free from in jurious salts; and the desert people, after every possible experiment, have long since ceased to anticipate any material supply for irrigation from that source.