report of the Commissioner of the General Land Office for the year

1902:

Areas of reserved and appropriated lands in the reclamation States on June 30, 1902. [Compiled from Report of Commissioner of the General Land Office,]

The arid regions of the United States, as generally designated, include about two-fifths of its entire area, extending from about the middle of the continent westerly nearly to the Pacific Ocean. There are no sharply marked lines or divisions between the arid and the humid areas, but there is, especially near the center of the United States, a broad intermediate belt, neither distinctly arid nor distinctly humid, which is called the subhumid or semiarid region. This belt extends over North Dakota, South Dakota, western Nebraska, and western Kansas into Oklahoma and the panhandle of Texas. In years of excessive moisture the subhumid region sometimes creeps up toward the foothills of the Rocky Mountains, while during dry years the greater part of the plains region west of the Missouri becomes semiarid. The relative extent of the regions of aridity is shown in fig. 2.

In a general way it may be said that the arid regions are those where the average annual rainfall is 20 inches or less. The arid regions of the United States, therefore, are but a portion of those of North America, there being large tracts of arid lands in Mexico on the south and in Canada on the north. In these countries the Government has

already recognized the importance of irrigation, and provision has been made for the reclamation of arid lands under public auspices. The Congress of the United States, in passing the reclamation law, has thus not been wholly without a precedent from other parts of the continent.

Aridity, or, rather, the unequal distribution of moisture, is largely the result of topography, or inequalities of land surface. If the globe were entirely flat it is probable that the winds, meeting with no obstructions, would distribute the rains with considerable uniformity in broad bands approximately parallel to the equator. The atmosphere enveloping the earth extends outward for many miles, but it is in the relatively thin and dense layer a mile or two in thickness resting immediately upon the surface that occur the changes or disturbances

FIG. 2.-Map showing arid, semiarid, and humid regions of the United States.

that make up what we know as weather. This thin layer of dense atmosphere surrounding the globe is disturbed in its uniform movement by the lofty mountain masses which traverse the continents. The movements of the air above this layer concern us little; it is the clouds and winds near the surface that bring success or failure to the farmer, and affect, more or less directly, other industries, and even health.

Taking the United States as a whole, the general movement of the atmosphere is from west to east. The moisture-laden winds from the Pacific, encountering the mountain masses which extend along or parallel to the coast, are forced upward and cooled. In winter they deposit much of their moisture on the mountains, and then pass eastward as dry winds, leaving the broad plains east of the Sierra Nevada dry, -terile, and desert-like in character. In the summer, however, when

the mountains have become relatively warm, the winds from the Pacific pass over them without leaving their moisture, and thus there results the summer drought characteristic of the Pacific coast. Passing onward, the winds, not deprived of humidity, give up from time to time portions of their precious fluid, and thus in the interior there are the occasional summer rains which tend to make amends for the deficient precipitation of the winter season. East of the Sierra Nevada and the Coast Range, and the plains and deserts at their bases, are scattered irregular mountain ranges and the great Cordillera or Rocky Mountain system, whose high summits intercept the rain-bearing winds. These mountain ranges are for the most part well watered while the lowlands are parched with drought. From the east face of the Rocky Mountains the high plains stretch out toward the Mississippi Valley, decreasing gradually in altitude to the rolling plains and prairies of the east-central States.

The above statements briefly outline what is known concerning the causes of aridity and the lack of uniformity of distribution of moisture across the continent. There are not only wide differences in various parts of the West and changes in succeeding seasons, but also great fluctuations in the quantity of rainfall from year to year. The actual excess or deficiency of rainfall as measured in inches may not seem great to the inhabitants of the humid East, but in the West when a shortage occurs the effects of the aridity are notably increased, and a large amount of water is needed to supply artificially the deficiency. Equal fluctuations in rainfall may occur in humid regions, but there the effects are not so marked. For example, in a country like that along the Atlantic seaboard, where the annual precipitation averages 50 inches, a deficiency of 10 inches during the year may not have an appreciable effect upon the crops and industrial conditions, but in a country where the annual rainfall is only 20 inches a deficiency of 10 inches may result in the disappearance of rivers and the destruction of the scanty vegetation so valuable in the cattle and sheep industries.

In the humid East the impression is rather general that aridity implies desert conditions, i. e., absence of vegetation, with naked rocks and sand glistening in the brilliant sunshine. On the contrary, the area of actual desert lands in the United States is relatively small. To the west of Great Salt Lake is what may be termed a true desert of sand and alkali, destitute of vegetation, except a few thorny or woody plants which occur at intervals; and in southern California, west of the Colorado River, is the Salton Desert, which embraces the bottom of an ancient arm of the Gulf of California, the land surface being in some places 300 feet below sea level, but shut off from the tides by the bars and ridges of mud brought down by the river. It is estimated that there are 70,000,000 acres of desert-like lands in the United States, areas which do not support any plants suitable for forage. The

remainder of the arid regions is covered with a more or less scanty vegetation of some value to mankind.

One-third of the United States, exclusive of Alaska and outlying possessions, consists of vacant public land. One of the great economic questions now before the people of the country is the utilization of this vast area, much of which has a rich soil, and under good management would be capable of sustaining a large population. These lands, however, have not been utilized to any considerable extent for the making of homes, but are passing into the control of speculators or large landowners.

The public lands are open to entry and settlement under what is known as the homestead law, the intent and purpose of which is to provide homes for the rapidly increasing population and permit an extension of the agricultural area as rapidly as the needs of the people demand. The object of the law is, however, not being accomplished, because of the fact that the lands are for the most part within the arid region, and crops can not be produced until a water supply has been obtained sufficient to moisten the soil during the growing season. There is a large amount of water that can be thus employed, but the expense of utilizing it is too great for the settler. The lands in localities where water can easily be diverted to the thirsty soil were taken up by the pioneers. In the early days it was possible for a man with a team and ordinary farm tools to construct ditches leading from the creeks flowing out of the mountains, and thus to provide channels by which his farm could be irrigated. In this way he was able to produce crops on the lowlands along the rivers, and gradually to extend the system of water supply to even the adjacent terraces or bench lands. The later comers, however, find that the small streams are already fringed with farms, and that the land lying beyond, although in many cases of better quality, can not be watered except at great cost.

The laws governing the disposal of public lands have been drawn almost wholly with reference to the broad prairies and plains of the Mississippi Valley, where the rainfall is sufficient to mature the crops. In that flat or gently rolling country every tract of 160 acres is practically as good as its neighbor, small differences of soil and surface erosion being excepted, and each farmer is independent as regards his method of cultivation, conducting his operations in the manner that his experience dictates. In the great arid region, however, where lies the larger part of the unoccupied public lands (see fig. 3), the value of the farm depends almost wholly upon the water supply, the accessibility and permanence of which far outweigh all other conditions. There the interests of all the farmers are closely related, for all depend upon streams or other sources of supply used in common, and independence must give way to cooperation. While the lands may be equally good as regards soil, their value may be far different because

of the fact that one tract of land has more water than another, so that the man who controls the water virtually owns everything of value. This fact has not been sufficiently recognized in framing laws governing the disposal of the public lands, and the result is that in many localities water monopoly is a powerful factor. In numerous instances title to a few hundred acres has virtually given possession to thousands of other acres, because the latter are rendered practically valueless by being cut off from participation in the water supply. In other words,

the creation of hundreds of homes has been prevented by neglecting to guard the right to the use of the scanty supply of water.

Without going into details, it is sufficient to state that the rectangular system of subdivision of the public lands, while one of the most beneficial measures leading to the settlement of the Ohio and Mississippi valleys, has been detrimental to the best growth of the western twofifths of the United States. This has arisen from lack of knowledge by the public, who are the owners, as to the part which irrigation plays in