30 
Modern Business Geography 
a 
1 
AB 
Fig. 17. Plants do not grow and produce crops in temperatures lower than 52°. The shaded 
belt in this map shows the area, north and south of the equator, in which agriculture goes oi 
during our winter. South of the southern line of 52° agriculture cannot be carried on. 
CLIMATIC CONDITIONS 
The temperature in the United States is highly favorable to farm- 
ing. The country is not located far enough to the north to have the 
extremely long winters that prevent agriculture in most of Canada 
and thus keep that country from reaping the full advantage of its 
size. Neither is it so far south that it is unfit for raising such crops 
as barley and wheat. It is fortunately placed, being in the latitudes 
where many of the crops most desired by the world markets can grow 
under ideal conditions of temperature. 
Effect of the uneven rainfall. In rainfall our country is not so 
fortunate as in temperature. The eastern half, to be sure, has as 
favorable a rainfall as any part of the world. Because it has frequent 
cyclonic storms and because no high mountains shut off the interior 
from the Atlantic Ocean and the Gulf of Mexico, this half receives 
rain in abundance. Most of the western half of the United States, 
on the contrary, gets too little rain for ordinary farming; the rain- 
bearing winds from the Pacific Ocean are unable to bring enough 
moisture over the high Sierra Nevada and Cascade Mountains. 
Nevertheless, cattle and sheep thrive on the dry grasslands to the 
east of these ranges. In the northern part of the Pacific slope, in 
several sections in California, and in the northern Rocky Mountain 
region, however, there is an abundant rainfall (Fig. 6).