ROUTE NEAR THE THIRTY-EIGHTH AND THIRTY-NINTH PARALLELS. Mi 
ROUTE NEAR THE THIRTY-EIGHTH AND THIRTY-NINTH PARALLELS OF NORTH LATITUDE. 
The general consideration that determined the position of the route to be examined near 
the 38th and 39th parallels of latitude, was its central position geographically, it being about 
midway between the northern and southern boundary lines of the United States, which is like- 
wise the position, nearly, of the Bay of San Francisco; the two termini of the route, St. Louis 
and San Francisco, being respectively in latitudes 39° and 38°, nearly. Moreover, a route 
near these parallels would probably give the shortest road from the Bay of San Francisco 
to the navigable waters of the Mississippi. 
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 been 
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 Rocky 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 rail- 
road route, 654 miles. 
Of the several passes through the Rocky mountains connecting the tributaries of the Huerfano 
with those of the Rio 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 Capt. Gunnison. 
By side location the summit, 9,219 feet above the sea, 692 miles from Westport, was attained, 
and the descent made to the valley of the Rio Grande with practicable though heavy grades; 
and thence the grades were favorable to the vicinity of Fort Massachusetts. 
The western chain of the Rocky 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, uncultivable plain, covered for the most 
part with wild sage, was ascended with easy grades to Sahwatch creek, one of whose affluents 
rises ina pass of the Rocky 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 numerous ravines. For 16 miles before the junction of Pass 
ereek with Coo-che-to-pa creek, the former passes through a broken cation. After following 
Coo-che-to-pa creek seven miles, the valley of Grand river is attained. 
The route follows the valley of this river 173 miles, then crosses the divide to Green river, 
68 miles, and by the tributaries of the latter approaches the pass through the Wahsatch mount- 
ains. A tunnel three-quarters of a mile long is here required, the eastern approach to which 
is by means of a grade of 125 feet per mile for 6} miles, and a descent to the west for 5 miles 
of 131 feet per mile. Thence westward along the valley of Salt creek for 18 miles the grade 
is 95 feet per mile, 16 miles of which is through a rocky cafion, intersected by lateral streams. 
The route then enters the valley of the Sevier, the exploration terminating on this river, 86 
miles further on, and 1,348 miles from Westport. 
From the western border of the State of Missouri to the Rocky mountains, 650 miles, no 
timber suitable for railroad purposes will be found, upon which reliance can be placed. From 
the Coo-che-to-pa Pass to the Great Basin, 500 miles, there is none available on the route, and 
the nearest supplies on the mountains bordering the Great Basin are in latitudes 40° and 41°. 
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