52 Gen. A. W.Greely — pMinfall Types of the United States. 



November, — .001, and December, .028. Similarly Colorado and 

 a portion of Texas to the eastward of the Pecos water-shed ex- 

 perience a composite type of rainfall arising from interference of 

 the Mexican type from the westward and the Missouri type from 

 the eastward. 



Colorado has its principal rainfall maximum in July or 

 August and its principal minimum in January, while the 

 secondary maximum occurs in April or May and a secondary 

 minimum in June. It is hardly necessary to state that certain 

 localities, according to their contiguity either to the simple 

 Mexican or the simple Missouri type in their rainfall, reverse in 

 order of importance the primary and secondary maxima and 

 minima here mentioned. 



Utah has a great diversit}^ of rainfall fluctuations, resulting 

 from its being so situated that it is more or less influenced from 

 different quarters by the Pacific, Mexican, and even the Missouri 

 type, the first named being most potent, especiall}^ in the western 

 and extreme northern part of the territory. 



The " Missouri " type of rainfall is the most important in the 

 United States, both from the vast area over which it obtains and 

 also from its extremely favorable bearing on agriculture. This 

 type dominates the water-sheds of the Arkansas, Missouri, and 

 upper Mississippi rivers and of lakes Ontario and Michigan, 

 as well as over Oklahoma and the greater part of northern Texas, 

 thus covering Montana, the Dakotas, Minnesota, Nebraska, 

 Kansas. Iowa, Missouri, Oklahoma, Wisconsin and Illinois, 

 together with parts of Arkansas, Texas, Michigan, Indiana and 

 Indian territory. 



The Missouri type indicates a very light winter precipitation, 

 followed in late spring and early summer by the major quantity 

 of the yearly rain. The area of country covered by this type is 

 so large that certain slight modifications could be antici^^ated. 

 For instance, while the June rainfall is as a rule the most abun- 

 dant, yet along the eastern slope of the Rocky mountains the 

 May rainfall is somewhat greater than that of the following- 

 month. Again, while January is usually the month of least 

 precipitation, yet in some localities the minimum has a ten- 

 dency to occur in December and in others to delay itself until 

 February. 



As examples of the Missouri type, there are here presented 

 rainfall data from Riley, Illinois, record of 39 years ; Muscatine, 



