The West 5 
CLIMATE 
The most noticeable feature of western climate is the 
limited rainfall, which is fairly well indicated in the ac- 
companying map (Fig. 2). It will be noted that with 
the exception of those parts of Oregon and Washington 
lying to the west of the Cascade Mountains, almost this 
Fie. 2. — Annual Rainfall of the United States. 
entire region has less than 20 inches of rainfall, while 
some parts, as in southern Nevada and Arizona, have even 
less than 10 inches. This dry climate, combined with 
the high altitude, tends to make the summers rather cool, 
particularly at night, although it may be quite warm in 
the sun during the day. The winters in such states as 
Arizona and New Mexico are very mild, while farther 
north, as in Montana, they are severe. The extreme dry- 
