No. 4, 
REPORT 
tJPON THE 
PROGRESS OE THE PACIFIC RAILROAD EXPLORATIONS AND SURVEYS. 
NO VEMBEE, 1856. 
BY CAPTAIN A. A. HUMPHREYS, UNITED STATES TOPOGRAPHICAL ENGINEERS. 
War Department, 
Office Pacific Railroad Explorations and Surveys , 
Washington, November 29, 1856. 
Sir: At the date of my last report, November 29, 1855, the party of Lieutenant John G-. 
Parke, topographical engineers, had just returned to Washington from the field. Since then 
it has been occupied in preparing the reports and maps of the survey, which are now nearly 
completed. 
By instructions from the department, of October 2, 1854, Lieutenant Parke was directed to 
make explorations to determine the practicability of constructing a railroad from the waters of 
the hay of San Francisco to the plain of Los Angeles, by the Salinas river valley, and through 
the spurs of the Coast range, which extend to the seacoast, near Point Concepcion ; or, if that 
was found to he impracticable, by the coast route; to make certain explorations in the Great 
Basin, in connexion with the route of the 35th parallel, and to explore the country between the 
Pimas villages on the Gila and the Rio Grande; the attention of the party being particularly 
directed to such examinations in the latter region as would show the degree of practicability of 
constructing artesian and common wells. 
The survey was commenced at San Jose, California. The route lay through the Santa Clara, 
or San Jose valley, to the Pajaro river ; down the valley of this stream to near its debouche 
into the hay of Monterey; around the foot hills of the Gavilan range of mountains to the 
Salinas plains and the valley of the Salinas river, and up the Salinas river to Santa Margarita, 
at the base of the San Luis pass. 
Thus far, no material obstacles were presented to the construction of a railroad; the Santa 
Clara valley and Salinas plains affording a peculiarly favorable location for it. A bridge across 
the Pajaro and some light earth work at the terminal spurs of Mount Gavilan, and in the valley 
of the Salinas, between the mouth of the San Lorenzo and Santa Margarita, constitute the 
