PHYSICAL CHARACTERISTICS OF THE ARID REGION. 23 
local improvements, it is essential that the residences should be grouped 
to the greatest possible extent. This may be practically accomplished by 
making the pasturage farms conform to topographic features in such man- 
ner as to give the greatest possible number of water fronts. 
PASTURAGE LANDS CANNOT BE FENCED. 
The great areas over which stock must roam to obtain subsistence 
usually prevents the practicability of fencing the lands. It will not pay to 
fence the pasturage fields, hence in many cases the lands must be occupied 
by herds roaming in common; for poor men cobperative pasturage is 
necessary, or communal regulations for the occupancy of the ground and 
for the division of the increase of the herds. Such communal regulations 
have already been devised in many parts of the country. 
RECA PITULATION. 
The Arid Region of the United States is more than four-tenths of the 
area of the entire country excluding Alaska. 
In the Arid Region there are three classes of lands, namely, irrigable 
lands, timber lands, and pasturage lands. — 
IRRIGABLE LANDS. 
Within the Arid Region agriculture is dependent upon irrigation. 
The amount of irrigable land is but a small percentage of the whole 
area. 
The chief development of irrigation depends upon the use of the large 
streams. 
For the use of large streams codperative labor or capital is necessary. 
The small streams should not be made to serve lands so as to interfere 
with the use of the large streams. 
Sites for reservoirs should be set apart, in order that no hinderance 
may be placed upon the increase of irrigation by the storage of water. 
TIMBER LANDS. 
The timber regions are on the elevated plateaus and mountains. 
The timber regions constitute from 20 to 25 per cent. of the Arid Region. 
