INTPvODUCTORY REMARKS. 



The chief object of my explorations during the past season was to 

 examine into and report upon the agricultural resources of Dal^Lota Ter- 

 ritorj' ; yet it was expected that I would at the same time extend my 

 observations to the immediately surrounding portions of the Northwest 

 similar in character and which might have any bearing upon the devel- 

 opment of the resources of Dakota. 



A slight examination of this section, added to the previous knowledge 

 I had obtained in regard to it, suiBced to convince me that, to thoroughly 

 understand its agricultural resources, it was important to investigate 

 the climatology and physical geography of the great prairie-belt lying 

 along the eastern margin of the great trans-Mississippi plains. 



Here, running north and south, is found the dividing line between 

 two regions and climates as different from each other as that of Europe 

 from that of Asia; here, in fact, in an agricultural, climatological, and 

 physical point of view, is the real dividing line between the eastern and 

 western portions of the continent. We have long looked upon the 

 great Rocky Mountain Range as the dividing line of the continent, and, 

 so far as the flow of water is concerned, this is so ; but the more this 

 region is examined the more apparent does it become that in other re- 

 spects this is far from being the rule. The chief dividing line between 

 the two great continental climatic areas stretches north and south along 

 the broad undulating plains of Kansas, Nebraska, Dakota, «&c., and 

 correspoilds very nearly with the one hundredth meridian. Here, too, 

 is the dividing line between great agricultural, faunal, and floral areas. 



In regard to climatology several important questions arise, two of 

 which deserve special attention, and which, if possible, should receive 

 at least approximately correct answers. The first relates to the isother- 

 mal lines through Wisconsin, Minnesota, and Dakota, especially the 

 lines of mean summer temperature. This is the more necessary from 

 the fact Wiat Mr. Blodgett,in his work on meteorology, has assumed that 

 the mean lines of summer temperature make a rapid bend northward 

 after passing west of Lake Michigan ; and this statement has been used 

 largely in the eflbrts to induce emigration to that portion of tbe North- 

 west. If it is true that this remarkable flexure does occur here, it must, 

 as a matter of course, have an important bearing upon our estimate of 

 the agricultural resources of this extensive region. I have, therefore, 

 made it a special object to test the correctness of this assumption by 

 all available data, which have been considerably increased since the 

 date to which Mr. Blodgett's calculations extend. Without intending 

 to forestall my investigations on this point, I may state that, while it is 

 true a very remarkable flexure in tbe isothermal lines does occur here, 

 yet the investigations I have made indicate that it is much less than Mr. 

 Blodgett represents it to be. 



The second climatological question relates to the rain-fall. It is well 

 known that on the east side of the plains, as in Minnesota, Iowa, Mis- 

 souri, and Arkansas, the average annual rain-fall is suflicient to supply 

 the moisture necessary for the production of the cereals and other agri- 

 cultural products. On the other hand, it is almost as well known that 

 irrigation is necessary at all points on the plains lying along the east 

 base of the Rocky Mountains. Therefore, it is evident that the boundary 



