The United States — Land and Waters 



8 



From M. A. Carleton, U. S. Department of Agriculture 



Combined Harvester-Thresher on One of the Vast Wheat Fields of the West 



would derive little rain from the Pacific. 

 We are indebted to these southwestern 

 Cordilleras for the fact that the rainfall 

 they conserve may be led down to the 

 California valleys turning them into 

 areas of wonderful fertility, the great 

 centers of our home production of semi- 

 tropical and some other fruits. We re- 

 member the time when the ' ' Great 

 American Desert ' ' was spread over most 

 of the western part of our maps. It has 

 now shrunk to very small proportions 

 indeed ; and the drier regions of the 

 country will some day be eliminated as 

 far as water can be obtained for their 

 reclamation. 



DISTRIBUTION OF RAINFALL 



At least 20 inches of rainfall a year 

 are required to make farming fairly 

 profitable and this is a scanty supply. 

 Nearly double that quantity falls in the 

 half of the country lying east of the 



1 ooth meridian and along the northern 

 three-fifths of the Pacific coast, and to 

 these regions is confined nearly our en- 

 tire development of agriculture except- 

 ing where stock is fed on the plains or 

 crops are irrigated. The profound in- 

 fluence which this unequal distribution 

 of rainfall has had upon our lordship 

 over the domain committed to us is 

 shown on many maps. A map showing 

 our density of population usually leaves 

 white most of the vast region west of 

 the 100th parallel ; a map showing the 

 distribution of our swine industry shows 

 its western frontier in central Nebraska, 

 Kansas and Texas because we fatten 

 hogs on maize which requires abundant 

 moisture ; a map illustrating cattle in- 

 dustries shows, the limit far to the west 

 of the region of swine for cattle can 

 thrive on grasses of the plains though 

 we drive many of them into the corn 

 belt to fatten. A map showing the 



