26 DRY-FARMING 



nation of this map proves that nearly one half of the 

 whole area of the United States receives 20 inches or 

 less rainfall annually; and that when the strip re- 

 ceiving between 20 and 30 inches is added, the whole 

 area directly subject to reclamation by irrigation or 

 dry-farming is considerably more than one half 

 (63 per cent) of the whole area of the United States. 

 Eighteen states are included in this area of low 

 rainfall. The areas of these, as given by the Census 

 of 1900, grouped according to the annual precipita- 

 tion received, are shown below : — 



Arid to Semi- Total Area Laxp ; 



ARID Group Surface (Sq. Miles) 



Arizona ...... 112,920 



California ...... 156,172 



Colorado 103,645 



Idaho 84,290 



Nevada 109,740 



Utah 82,190 



Wyoming 97,575 



Total 746,532 



Semiarid to Sltb-hi'mid Group 



Montana 145,310 



Nebraska 76,840 



New Mexico 112,460 



North Dakota .... 70,195 



Oregon 94,560 



South Dakota .... 76,850 



Washington 66,880 



Total 6.53,095 



