16 INTRODUCTORY REMARKS. 
Lieutenant James Abert’s report of reconnaissances in New Mexico in 1846, Captain A. W. 
Whipple’s report of survey of railroad route near the 35th parallel, and elsewhere. 
A valuable history of the progress of early discoveries on the western coast of North America 
can be seen in a French work by M. Duflot de Mofras, published in 1844, and also in Mr. Robert 
Greenhow’s book on Oregon and California, published in 1845. This last work is accompanied 
by a map ‘‘of the western and middle portions of North America," compiled by Mr. Greenhow. 
. An elaborate work upon the early discoveries on the coast of America, both upon the Atlantic 
and Pacific shores, has lately been prepared for the United States Coast Survey by Dr. J. G. 
Kohl. It will appear in the printed papers of the Coast Survey. 
The first exploration which seems to require a detailed notice is that of Captains Lewis and 
Clarke, United States army, directed by President Jefferson in 1803. The small map herewith 
presented exhibits the knowledge possessed of our present territory west of the Mississippi 
river before this exploration was made. 
As the explorations are mentioned in order of date, the various examinations in the same 
region, or along the same route or river, are necessarily separated. To avoid the difficulty 
which this arrangement presents in making a prompt reference to all the sources of information . 
of any one subject, an index has been prepared, which will be found at the end of this memoir. 
The political and military divisions of the country are taken in the index as T" Mota on the 
first edition of the map, which was correct at the date of this report. 3 
