REPORT OF°THE SECRETARY OF WAR. 
War DEPARTMENT, 
Washington, February 27, 1855. 
Str: I have the honor, in obedience to the provisions of the 11th section of the army appro- 
priation act, approved March 31, 1858, to lay before Congress printed reports of the engineers 
employed under the provisions of that act to make such explorations and surveys as this 
department might,deem advisable, in order to ascertain the most practicable and economical 
route for a railroad from the Mississippi river to the Pacific ocean. 
The great amount of labor required in the preparation of the general map, originally de- 
signed to accompany this report, and the unfinished condition of the original maps and other 
data, have delayed its completion beyond the period anticipated, but it is confidently believed 
that its engraving will be finished in time to accompany the extra copies of the report ordered 
by the two houses of Congress. It embraces the territory of the United States between the 
great lakes and the Mississippi river, on the east, and the Pacific ocean on the west. It is based 
upon the most reliable astronomical data within those limits; and the details having been 
compiled with care, from all the government explorations and surveys and other reliable 
authorities, it will present more minute information upon the region embraced by it than has 
heretofore been exhibited on any general map. It will show the relation to each other of the 
different railroad routes recently explored, their connexions with prominent points on Lakes 
Superior and Michigan, the Mississippi river and the Gulf of Mexico, and with the ports of the 
Pacific ; and, exhibiting only such features as have been determined by reliable observers, it 
will be of great value in showing what further explorations are necessary, and in determining 
their direction and extent. 
I have heretofore reported the nature of the explorations and surveys ordered in compliance 
with this act ; and by a reference to the statements there made, it will be seen that in order to 
accomplish as much as possible within the limited period indicated, not only were there as 
many distinct corps employed as there were routes to be surveyed, but several parties were, in 
some cases, employed upon different sections of the same route. It appears, therefore, necessary, 
in submitting these several reports, many of which are quite voluminous and in detached parts, 
to present a general recapitulation of their results, indicating those distinguishing characteristics, 
the comparison of which will determine which of the routes surveyed best fulfils the condition 
of practicability and economy proposed by the act. 
I will here repeat the general sketch of the country given in my first annual report, but 
corrected in accordance with the results of the recent explorations. This will serve, in the 
absence of a more elaborate description, to give some general idea of the nature of the country 
over which they extended. 
‘The western portion of the continent of North America, irrespective of the mountains, is 
traversed from north to south by a broad, elevated swell or plateau of land, which occupies the 
greater portion of the whole space between the Mississippi river and the Pacific ocean. The 
crest of this plateau, or the water-shed of the country, is nearly midway between the Pacific 
coast and the Mississippi. It may be represented on the map by an undulating line traced 
