ROCKY MOUNTAIN PASSES. 99 
difficulty, and involve a considerable detour as regards the approach from the north of the Mis- 
sourl. 
The northern Little Blackfoot Pass is the one by which Mr. Tinkham crossed the Rocky mount- 
ains the third time, and in November; is at the source of one of the north forks of Hell Gate river, 
termed by Lieutenant Mullan Little Biackfoot river, and is remarkably easy. The Indian trail 
passing here is a well-worn road, and is perfectly practicable for wagons. The dividing ridge is 
an inconsiderable hill, three hundred to five hundred feet high. Between this pass and the prairies 
of Marias, Teton, and Sun rivers, the country is somewhat irregular and broken. The barometer 
gave the summit elevation of the pass at 6,250 feet above the sea, which will probably, in a 
discussion of the observations, be reduced to less than 6,000 feet. 
In pursuing this route, Mr. Tinkham kept south of the Missouri until the gate of the mountain 
was turned; and for information of the approach north of the Missouri, | am indebted to an 
exploration under Lieutenant Mullan. In a trip to Fort Benton and back to the St. Mary’s 
valley in March, Lieutenant Mullan brought a wagon through this pass, making the journey from 
Fort Benton to Cantonment Stevens, a distance of two hundred and ninety-six miles, in twelve 
travelling days; and there seems scarcely a doubt as to there being an excellent railroad approach 
to it north of the Missouri, on the route pursued by him. He kept on the high table-land between 
the Missouri and the Teton, crossed the Sun and the Dearborn rivers a little south of the crossing 
of the main party in September last; then keeping farther to the south, he crossed the small 
Prickly Pear creek, and crossing a divide, the one taken by Mr. Tinkham in November, he 
found the inclination so gradual, that he descended from it not only without locking wheels, but 
ona run. His course then was by the Little Blackfoot and Hell Gate rivers. A little work is 
required on this route in cutting timber to get an excellent wagon road. The eastern approach 
is estimated as practicable with a grade of fifty to sixty feet per mile, the passage of the ridge 
with a two-mile tunnel, and the western descent with a grade of thirty feet. The valleys of the 
Little Blackfoot and Hell Gate rivers, from the pass to the junction with the Blackfoot river, are 
more open and regular than the valley of the latter. Its descent is regular, and, by the barometric 
observations, is, from the foot of the summit divide to Hell Gate, ninety-five miles, twenty-two 
and a half feet per mile. The route for the greater portion of the way keeps on the bottom-lands, 
which are generally unobstructed by timber, sufficient wood always lining the streams for use as 
fuel, whether for camping or settlement. For lumber, the woods of pines and other evergreens 
are sufficiently near for use; but the thick woods do not crowd the valley as in some places 
on Blackfoot river. An open growth of yellow pme occupies the bottom-lands for a few miles 
in the lower part of the valley, and the cotton-wood growth sometimes stretches across. the bottom. 
The construction of a railway down this valley will probably make necessary the bridging or 
turning of the main stream several times. Curves will be easy, and the grades used not gene- 
rally exceed the natural descent of the valley. 
The route is indicated on the sketch in dotted lines. It will increase the route forty-four 
miles, but it may give the means, at the eastern extremity of the Little Blackfoot valley, to 
make a junction with a road trom Council Bluffs. This connexion is indicated on the map. The 
mountains shutting down on the Missouri, on both banks, to the gate of the mountains, may pre- 
sent an earlier junction of the two routes. The thorough examination of this route, and of the 
Little Blackfoot trails, with which it connects almost immediately west of the divide, and of 
the Hell Gate Pass, all three of which have been examined by Lieutenant Mullan, and the full 
description of which will be found in his reports herewith submitted, will become important should 
a good connexion be found through the Black Hills with the roads moving westward through 
Towa and Missouri; or, should it be found practicable, through the same hills to make a straighter 
route from the Bois des Sioux than that north of the Missouri. i 
The southern of the Little Blackfoot routes is singularly direct, and, in common with the Hell 
Gate route and northern Little Blackfoot, requires little or no labor to make it practicable for 
