IRRIGATION. It was not until after the humid region had been generally settled that the arid region was occupied. The Mormons, in 1S47, were the first to practice irrigation in the West. In 1870 there were only 20.000 acres irrigated. In the Great American Desert the area at present under irrigation and cultivation is insignificant as compared with the uncultivated portion. It is estimated that the water supply is sufficient to irrigate only one-fifth of the arid region.
The decade 1870-80 was characterized by rapid development of small ditches. In the lat ter year there were about 1.000,000 acres ir rigated. The following decade was characterized by rapid construction of canals, nearly all of which resulted financially in failures. In many instances the supply does not equal the demands placed upon the canals. There are now hut few unused sources from which water can be largely obtained. Hereafter the extension of the irriga tion system will depend mainly upon the con struction of large reservoirs. Irrigation has suf fered much from the want of adequate laws. In only three States—Colorado, Nebraska. and Wyoming—is the system of supervision and con trol complete. In several States no public c•on t•o] is exercised. The laws are often indefinite or contradictory. There have arisen disputes as to the rights of the different States to the use of a streann which may pass through their territories.
In 1902 a new act was passed by Congress which provided that the Department of the Interior should deal with questions of the water supply, and the location. construction, and management of irrigation works. Receipts from the dis posal of public lands are set aside for construc tion works. Water is to he furnished both to public and private lands. Before the beginning of survey for contemplated works, the Secretary of the Interior is to withdraw from entry. except under homestead laws, any land that may be irrigated from such works. In anticipation of the rise of land talues through national irriga tion, there was a rush of speculators who, through a perversion of the intention of the Desert Land Law, the Timber Law, and the com mutation clause of the Homestead Law, acquired large areas without actual settlement. The fol lowing table shows the status of irrigation in the arid States and Territories: The table on page 661 shows the development and the distribution of the four largest crops. The-3e. together with cotton, are by far the most important crops in the United States, consti tuting over nine-tenths of the entire crop area.