ROUTE NEAR THE FORTY-SEVENTH AND FORTY-NINTH PARALLELS, 41 
After reaching the Missouri, the line follows the valley of this stream to the mouth of Milk 
river, 120 miles from Fort Union, then ascends the valley of Milk river, 187 miles, the erades 
rarely exceeding the river-slopes, (the Missouri being one foot per mile, the Milk three feet 
per mile,) with an average embankment of eight feet, and with but little rock excavation, 
and that in soft sandstone. The river bottoms, composed of clay and sand, are soft and 
sloppy in wet weather, and parched and cracked during the dry season. As the Rocky mount- 
ains are approached, the country bordering the Missouri river is rough and broken; nearer the 
mountains, prairies afford more favorable ground for location. 
Having turned the Bear’s Paw mountains, lying between the Milk and Missouri rivers, the 
line leaves the valley of Milk river and rises to the prairie, with a grade of thirty-five feet per 
mile, taking a southwest direction towards the passes in the Rocky mountains, which lie near 
the 47th parallel of latitude, crossing in its course the Maria’s and Teton rivers with grades of 
forty feet per mile, and the Sun river without difficulty, the whole distance being about 440 
miles. 
The cotton-wood of the Missouri and Milk rivers not being suitable for building material, 
except for a temporary road, by which to build the permanent one, this portion of the route is 
dependent upon the pine of the Trois Buttes mountain, (sleepers for 300 miles single track from 
this source,) of the Rocky mountains, and of the mountains south of Fort Benton. Good 
sandstone is to be found near Fort Union, at the crossing of Milk river, and at the Trois 
Buttes; lime near Fort Union, the Trois Buttes, and the Rocky mountains; clay, for brick, 
on the Missouri and Milk rivers; and sand in the beds of the rivers, though not abundant, in 
a clean state. 
If cotton-wood cannot be used as fuel, we have on this route spaces of 100, 200, and 400, or 
500 miles between the points of supply; that is, 200 miles from the Red river supply to that of 
the Mouse river; 400 miles from the Mouse river supply to that of the Bear’s Paw, or 500 to 
that of the Trois Buttes; and from the Trois Buttes to the Rocky mountain supply, not less 
than 100 miles. The supplies of lumber are the same as for fuel. 
At what distances apart large supplies of water can be had from the Red River of the North 
to Maria’s river is not stated. The rivers along which the road runs cannot alwaye be relied 
upon for it, since the road is immediately under the bluffs of the valley, and the small streams 
are dry in summer, and so of the ponds on the prairies; both in extreme dry and hot seasons, 
and in the winter, there would be deticieucies. The high plateaux making back from these 
rivers, it is thought, will afford the means of securing, by reservoirs, ample supplies. The 
precise data upon which this opinion is formed are not given; the number, capacity, and posi- 
tion of the ponds or small lakes proposed to be used are not stated, nor the distances at which 
the reservoirs can be made. 
Between the Maria’s and Sun rivers, Grizzly Bear lake is indicated as a point of supply. 
From the Bois des Sioux to Riviére 4 Jacques is about 120 miles. From Riviére a Jacques 
to Butte de Maison, where probably the ponds of the Coteau du Missouri could give a large 
supply of water, is 115 miles. Thence to head of Riviere des Lacs, 120 miles. Thence to 
mouth of Big Muddy, on the Missouri, 120, &c. There can be no doubt that supplies of 
water at these distances can be got during all seasons, which may be made to answer for rail- 
road purposes, though not sufficient for working parties. 
The line has now reached the base of the Rocky mountains, and an elevation, where it may 
enter the passes through them, of 4,700 feet above the sea. 
In deciding upon the route by which the road should cross this mountain chain, regard 
must be had, not only to the difficulties of approach to the passes and the difficulties in the 
passes, but also to the best pass (from every consideration) of the Bitter Root mountains. 
This last is a secondary mountain chain lying west of the principal, separating from it in 
about latitude 45° 30’, and running northward and westward into the British possessions. 
Flowing in the valley, between these two chains, are the Flathead and St. Mary’s or Bitter 
64 
