RAINFALL IN NEBRASKA. 47 



adjoining it. And it is a remarkable fact, that last winter, (1S79), 

 there was an exceptionally large fall of snow, and this summer an 

 abundant rainfall in the same region. In fact, this snow and rain- 

 fall extended all over Western Nebraska. 



The question is often asked whether the causes now producing 

 the increased rainfall over the eastern two-thirds of the State will 

 ever be sufficiently operative over the extreme western third as to 

 make it an agricultural region. Of this I have no doubt. It prob- 

 ably will take a longer time to produce this change here than it 

 did in eastern Nebraska. The cause of this will be discussed pres- 

 ently. When the great body of the land near to and west of the 

 100th meridian is once cultivated that is capable of cultivation, the 

 sufficiently and increasingly moist region will encroach gradually 

 on the dry region until it is entirely crowded out of the State. 

 And the reason why this cause will be slower here in its operation 

 is because extreme western Nebraska is under the lee of the Rocky 

 Mountains. The moisture-bearing winds do not strike it so direct- 

 ly as they do eastern Nebraska. This is better understood when 



The Original Sources of the Rainfall of Nebraska 



are Considered. 



These sources are mainly of a two-fold and combined character. 

 One source is the moisture-laden winds from the Gulf of Mexico; 

 the other is the enormous evaporation from those rivers of Nebras- 

 ka that have their source in the Rocky Mountains. 



Rains are most apt to fall when there is a change in the direc- 

 tion of the winds. If the wind, for example, has been blowing for 

 days from the southwest, south, or southeast, and turns around and 

 comes from the north, rain is almost certain to fall. There will 

 also be a fall of rain if the change is from the north to the south. 

 Any one looking at a map of the United States will see that the 

 south wind coming directly upon the west end of the Mexican 

 Gulf, would strike Red Willow, Furnas, Dawson, Custer, Elk- 

 horn, and Knox counties. Whenever, therefore, all of Nebraska, 

 including these and the counties east of them are bathed by this 

 moisture-bearing wind from the Gulf, either after a north wind or 

 followed by one there is precipitation of moisture into cloud and 

 generally rainfall. When the wind is slightly from the southeast, 

 extreme western Nebraska shares in this rainfall, otherwise it does 

 so to only a limited extent. This is, it appears to me, one reason 



