84 Explorations and Surveys for the Pacific Railroad. 



In the absence of instrumental surveys affording data for the 

 construction of profiles, no opinion can be formed as to the prac- 

 ticability of this route for a railroad. Should it be found practi- 

 cable, however, it will lessen the length of the route of the 41st 

 parallel, and still further diminish its difficulties, already known 

 to be less than on any other route except that of the 32d parallel. 



Route near the thirty-eighth and thirty-ninth parallels of north 

 latitude. — The exploration of the route conducted by Captain J. 

 W. Gunnison, corps of Topographical Engineers, commenced on 

 the Missouri at the mouth of the Kansas, about 245 miles from 

 the Mississippi at St. Louis. The Kansas, and its branch called 

 the Smoky Hill fork, were followed to a convenient point for 

 crossing "to the Arkansas, the valley of this latter river having 

 entered west of the Great Bend and near the meridian of 99°. 

 The route then ascended the valley of the Arkansas to the 

 mouth of Apishpa creek, fifty miles above Bent's Fort ; leaving 

 it here, and crossing to the entrance of the Eocky mountains, 

 here called the Sierra Blanca, at the Huerfano Butte, on the 

 river of that name, a tributary of the Arkansas. The elevation 

 at this point is 6,099 feet; its distance from Westport, mouth of 

 the Kansas river, by the railroad route, 654 miles. 



Of the several passes through the Eocky mountains connect- 

 ing the tributaries of the Huerfano with those of the Eio del 

 Norte, but one, the Sangre de Cristo, was found practicable for 

 a railroad, the new and only practicable approach to this pass 

 being explored by Captain Gunnison. By side location the sum- 

 mit, 9,219 feet above the sea, 692 miles from Westport, was at- 

 tained, and the descent made to the valley of the Eio Grande 

 with practicable though heavy grades ; and thence the grades 

 were favorable to the vicinity of Fort Massachusetts. 



The western chain of the Eocky mountains is now to be 

 crossed in order to gain and traverse the basins of the two great 

 tributaries of the Colorado of the West, Grand and Green rivers. 

 For this purpose the valley of San Luis, an extensive, unculti- 

 vable plain, covered for the most part with wild sage, was as- 

 cended with easy grades to Sahwatch creek, one of whose afflu- 

 ents rises in a pass of the Eocky mountains, here called the 

 Sahwatch mountains, known by the name of the Coo-che-to-pa 

 Pass. 



The approach to the summit of the pass, 10,032 feet above 

 the sea, 816 miles from Westport, is not favorable, the pass in 

 this part having a defile character, overhung occasionally by 

 walls of igneous rock. To cross the summit, a grade of 124 

 feet per mile for several miles, and a tunnel nearly two miles 

 long are required. The descent, with grades varying from 41 to 

 108 feet per mile, is by the valley of Pass creek, along which 

 much cutting and filling will be necessary, as the hills are cut by 



