4 LANDS OF THE ARID REGION OF THE UNITED STATES. 
infrequent. In the western portion agriculturists will early resort to irri- 
gation to secure immunity from such disasters, and this event will be 
hastened because irrigation when properly conducted is a perennial source 
of fertilization, and is even remunerative for this purpose alone; and for 
the same reason the inhabitants of the eastern part will gradually develop 
irrigating methods. It may be confidently expected that at a time not far 
distant irrigation will be practiced to a greater or less extent throughout 
this Sub-humid Region. Its settlement presents problems differing mate- 
rially from those pertaining to the region to the westward. Irrigation is not 
immediately necessary, and hence agriculture does not immediately depend 
upon capital. The region may be settled and its agricultural capacities 
more or less developed, and the question of the construction of irrigating 
canals may be a matter of time and convenience. for many reasons, much 
of the sub-humid belt is attractive to settlers: it is almost destitute of for- 
ests, and for this reason is more readily subdued, as the land is ready for 
the plow. But because of the lack of forests the country is more depend- 
ent upon railroads for the transportation of building and fencing materials 
and for fuel. To a large extent it is a region where timber may be success- 
fully cultivated. As the rainfall is on a general average nearly sufficient 
for continuous successful agriculture, the amount of water to be supplied 
by irrigating canals will be comparatively small, so that its streams can 
serve proportionally larger areas than the streams of the Arid Region. In 
its first settlement the people will be favored by having lands easily sub- 
dued, but they will have to contend against a lack of timber. Eventually 
this will be a region of great agricultural wealth, as in general the soils are 
good. From our northern to our southern boundary no swamp lands are 
found, except to some slight extent in the northeastern portion, and it has 
no excessively hilly or mountainous districts. It is a beautiful prairie 
country throughout, lacking somewhat in rainfall; but this want can be 
easily supplied by utilizing the living streams; and, further, these streams 
will afford fertilizing materials of great value. 
The Humid Region of the lower Columbia and the Sub-humid Region 
of the Great Plains have been thus briefly indicated in order that the great 
Arid Region, which is the subject of this paper, may be more clearly defined. 
