THE DOMAIN FOR DRY FARMING 49 



very small portion of Washington, Oregon and Wyoming 

 is the rainfall thus low. In practically all the intervening 

 portions of the dry country it runs from 10 to 20 inches. 

 The territory in Canada classed as semi-arid includes con- 

 siderable areas in southern Alberta and Saskatchewan 

 and a limited area in southwestern Manitoba. Canada 

 has no land virtually that should be classed as arid. On 

 the supposition that the arid and semi-arid area lies be- 

 tween the meridians 100 and 120 west longitude, and be- 

 tween parallels 53 and 30 north latitude, the width of this 

 area is about 1,400 miles from east to west, and the length 

 about 1,600 miles from north to south. Within this area 

 are 1,436,000,000 acres. There is no means of knowing 

 with certainty at the present time the relative proportions 

 of this vast area that are untillable, because rough, rocky 

 and mountainous, but the estimate would seem low that 

 would consider only two-fifths of the entire area tillable. 

 Computing on this basis would give practically 573,000,- 

 000 acres of land in the dry country that is tillable. On 

 the supposition that 73,000,000 acres of this land is in 

 Canada, it would still leave 500,000,000 acres for the 

 United States. Not more, probably, than 100,000,000 

 acres can ever be irrigated. This would leave 400,000,- 

 000 acres of tillable land in the semi-arid states of the 

 west, which never can be farmed successfully except by 

 dry farming methods. When it is further considered 

 that nearly all of this land is of surpassing richness, the 

 magnitude of the dry land farming question to the United 

 States will be at once apparent. The estimate of Widt- 

 soe is even more liberal. It places the entire area that 

 may be tilled at 600,000,000 acres, of which not to exceed 

 5 per cent, will ever be irrigated. 



Divisions of the arid and semi-arid areas. The arid 

 and semi-arid areas may be grouped as follows: (1) the 

 Great Plains area; (2) the Inter-mountain region; (3) the 

 Columbia river basin ; (4) the Great Basin, and (5) the 



