20 ROUTE NEAR THE THIRTY-FIFTH PARALLEL. 
ROUTE NEAR THE THIRTY-FIFTH PARALLEL OF NORTH LATITUDE. 
The general features which have determined the position of this route, the exploration 
of which was conducted by Lieut. A. W. Whipple, Topographical Engineers, are the exten- 
sion, west and east, of the interlocking tributaries of the Mississippi, the Rio Grande, and the 
Colorado of the West. It would appear to possess also a greater yearly amount of rain than 
the regions immediately north and south of it—and, as a consequence, a better supply of fuel 
and timber. 
Commencing at Fort Smith, on the Arkansas river, about 270 miles from the Mississippi 
at Memphis, the route, as far as the Antelope Hills on the Canadian, a distance of 400 miles, 
may follow either the valleys of the Arkansas and Canadian, or a shorter line perhaps, but 
over more ground, south of the Canadian, this latter route branching again, and following 
either the valley of the Washita, or the dividing ridge between it and the Canadian. 
From the Antelope Hills the route continues along the bottom of the Canadian, on the 
right bank, to the mouth of Tucumcari creek, about 250 miles, and ascends by the valley of 
Tucumeari, or by that of Pajarito creek, to the dividing-ridge between the Canadian and the 
Pecos rivers, elevation about 5,543 feet, and enters the valley of the latter. It follows this 
valley until, by means of a tributary, it rises to the high table-land, or basin, lying east of 
the Rocky mountains, elevation about 7,000 feet, crosses the elevated Salinas basin, 30 miles 
wide, the lowest point being 6,471 feet, and gains the divide in the Rocky mountains, eleva- 
tion about 7,000 feet; from which point it descends to Albuquerque, or Isleta, on the Rio 
Grande, through the San Pedro Pass; or it may descend to the Rio Grande by the valley 
of the Galisteo river, north of Sandia mountain. A third route is indicated along the valley 
of the Pecos to its headwaters; thence to an affluent of the Galisteo ; and thence, as before, 
to the Rio Grande. 
Isleta, on the Rio Grande, is 854 miles from Fort Smith, and 4,945 feet above the sea. 
Crossing the ridge separating the Rio Grande from the Puerco, the route follows the valley © 
of its tributary, the San José, to one of its sources in a pass of the Sierra Madre, called the 
Camino del Obispo; at the summit, (elevation 8,250 feet,) a tunnel three-fourths of a mile long, 
at an elevation not less than 8,000 feet, is required, when the descent is made to the Zuni 
river and near the Pueblo of Zuni; the route then crosses, over undulating ground, to the 
Puerco of the West, at the Navajo spring. 
Another route across the Sierra Madre, about twenty miles further north, was examined by 
Mr. Campbell, which is apparently far more favorable. The profile, however, is not from 
reliable instrumental examination. The height of the summit is about 7,750 feet above the sea. 
The Puerco of the West heads in this pass, and the route follows the valley of this stream, 
(intersecting the other line at Navajo spring,) to its junction with the Colorado Chiquito; then 
the valley of that stream to the foot of the southeastern slopes of the San Francisco mountains, 
elevation 4,775 feet; distance from Fort Smith 1,182 miles, and from the crossing of the Rio 
Grande 328 miles. Here it ascends to the dividing ridge between the waters of the Gila on 
the south, and of the Colorado of the West on the north, and continues (or nearly so) upon it 
for about 200 miles, to the Aztec Pass, elevation 6,281 feet ; distance from Fort Smith 1,350 
miles. The highest point reached upon this undulating ridge is 7,472 feet, at Leroux’s 
spring, at the foot of the San Francisco mountain. From the Aztec Pass, the descent to 
the Colorado of the West is made by a circuitous route northward along valleys of its tribu- 
taries, the largest and last being Bill Williams’s fork, the mouth of which, on the Colorado, 
is 1,522 miles from Fort Smith, and at an elevation above the sea of about 208 feet. 
The Colorado is now ascended 34 miles, when the route, leaving it at the Needles, follows 
what was erroneously supposed to be the valley of the Mohave river, but which proved to be 
the valley of a stream, dry at the time, whose source was in an elevated ridge, which probably 
divides the Great Basin from the waters of the Colorado. The summit having been attained, 
