12 ROUTE NEAR THE FORTY-FIRST AND FORTY-SECOND PARALLELS. 
The work upon this route, under Governor Stevens, embraced a wider field of exploration 
than that upon any other explored, and a great amount of topographical and general inform- 
ation was collected in relation to the country traversed. The necessary astronomical observa- 
tions were not made to determine accurately the longitudes of the several stations, and the loss 
of his barometrical observations, after the completion of the field-work, left no means of revising 
and verifying the profile of the route. 
The examination of the approaches and passes of the Cascade mountains, made by Captain 
McClellan, of the Corps of Engineers, presents a reconnaissance of great value, and though 
performed under adverse circumstances, exhibits all the information necessary to determine 
the practicability of this portion of the route, and reflects the highest credit on the capacity 
and resources of that officer. 
ROUTE NEAR THE FORTY-FIRST AND FORTY-SECOND PARALLELS OF NORTH LATITUDE. 
About one-half of the route in this latitude, extending from the Missouri river to Fort 
Bridger, on a tributary of Green river, has not been explored with a special reference to the 
practicability of constructing a railroad, and the reports do not contain all the details neces- 
sary to the elucidation of the subject. The information respecting it is to be found in the 
reports of Col. Fremont and Capt. Stansbury. 
From Fort Bridger to Fort Reading, on the Sacramento river, the exploration has been 
made by Lieut. HE. G. Beckwith, under the appropriation for that purpose. 
The route may commence on the Missouri, either at Fort Leavenworth, about 245 miles 
from the Mississippi at St. Louis, or at Council Bluffs, about 267 miles from the Mississippi at 
Rock Island, ascend the Platte and enter the eastern chain of the Rocky mountains (the Black 
Hills) by the North fork and its tributary, the Sweet Water. Another route, by the South fork 
and a tributary called Lodge Pole creek, has been suggested by Capt. Stansbury as shorter and 
less expensive; but the information respecting it is not sufficiently full to make further 
mention of it necessary. 
From the Missouri river to the entrance of the Black Hills, 30 miles above Fort Laramie, 
520 miles from Council Bluffs, and 755 miles from Fort Leavenworth, the route resembles 
others from the Mississippi to the Rocky mountains, and needs no special mention. Its cost 
per mile will be about the same. 
The route west of this point crosses many lateral streams that have cut deep ravines into 
the soil, and leaves the Platte just below the Hot Spring Gap, above which it is walled in by 
cafions. To avoid these, the route crosses a range of hills 800 feet above the river, and descend- 
ing to the Sweet Water, a branch of the Platte, follows that stream to its source, where the 
summit of the plateau of the South Pass (elevation 7,490 feet) is attained. The valley of the 
Sweet Water is generally rather open, but occasionally it cuts through mountain spurs, forming 
cajions. 
From the first gorge in the Black Hills to the summit of the pass, 291 miles, the work will 
be difficult and expensive, and is assimilated in amount to that of the Baltimore and Ohio 
railroad, 
From the South Pass the route follows down Sandy creek, a tributary of Green river, to 
the crossing of the latter, and thence to Fort Bridger, (elevation 7,254 feet,) on Black’s fork, 
likewise a tributary of Green river. The amount of work on this section would be consid- 
erably less than on the preceding. 
From Council Bluffs to Fort Bridger the distance is 942 miles; from Fort Leavenworth 
1,072 miles. 
The route now ascends the divide between the waters of Green river and those of the Great 
Salt lake, by the valley of Black’s fork, or of one of its tributaries, with grades of 69.5 and 
40.3 feet per mile. The summit is a broad terrace at the foot of the Uinta mountains, and 
has an elevation of 8,373 feet. From this point the line descends over the undulating country 
