THE DOMAIN FOR DRY FARMING 53 



Bureau of Plant Industry, U. S. Department of Agricul- 

 ture in 1910/ 



In North Dakota the average annual precipitation is 

 17.95 inches, the maximum 27.03 and the minimum 12.3. 

 About one-sixth of the area, embracing the eastern and 

 especially the southeastern portion of the state, has an 

 annual precipitation of 20 inches and above that amount. 

 About one-fifth of the area lying in the northwest and 

 to a greater extent in the southwest, has a rainfall of 15 

 inches and less. The rest of the state has a precipitation 

 of 15 to 20 inches. The lowest precipitation is in the 

 southwestern counties, where it averages about 13 inches. 



In South Dakota the average annual rainfall is 20.9 

 inches, the maximum is 29.7 and the minimum 9.7. Some- 

 what more than the eastern third has a rainfall of 20 

 inches and upwards, and the same is true of a small area 

 in the Black Hills regions in the west. The greater 

 portion of the western third is less than 15 inches. A 

 somewhat limited area in the central western portion is 

 from 15 to 20 inches. 



In Nebraska the average annual precipitation is 

 25.79 inches, the maximum 35.8 and the minimum 13.3. 

 Only in the western third of the state is the rainfall less 

 than 20 inches, and in but few counties within that area 

 is it less than 30 inches. 



In Kansas the average annual precipitation is 29.05 

 inches, the maximum 44.5 and the minimum 16.1. Only 

 in about one-sixth of the western portion is the rainfall 

 less than 20 inches. The increase is gradual and con- 

 tinuous to the east. The southeastern part of the state 

 has a precipitation of more than 40 inches annually. 



In Oklahoma the average annual precipitation is 

 34.75 inches, the maximum 45.3 and the minimum 15.5. 

 Only in the three most westerly counties is it less than 

 20 inches. In the eastern portion of the state and com- 



