vation of this pass at about seven thousand feet; a correct observation with a good barometer enables me now to give it with more precision. Its importance, as the great gate through which commerce and travelling may hereafter pass between the valley of the Mississippi and the north Pacific, justifies a precise notice of its locality and distance from leading points, in addition to this statement of its elevation. As stated in the report of 1842, its latitude at the point where we crossed is 42° 24' 32"; its longitude, 109° 26′ 00′′; its distance from the mouth of the Kanzas, by the common travelling route, nine hundred and sixty-two miles; from the mouth of the Great Platte, along the valley of that river, according to our survey of 1842, eight hundred and eighty-two miles; and its distance from St. Louis about four hundred miles more by the Kanzas, and about seven hundred by the Great Platte route; these additions being steamboat conveyance in both instances. From this pass to the mouth of the Oregon is about one thousand four hundred miles, by the common travelling route; so that, under a general point of view, it may be assumed to be about half way between the Mississippi and the Pacific Ocean, on the common travelling route. Following a hollow of slight and easy descent, in which was very soon formed a little tributary to the Gulf of California (for the waters which flow west from the South Pass go to this gulf), we made our usual halt four miles from the pass, in latitude, by observation, 42° 19′ 53′′. Entering here the valley of Green

river,

the great Colorado of the West, — and inclining very much to the southward along the streams which form the Sandy river, the road led for several days over dry and level uninteresting plains, to which a low, scrubby growth of artemisia gave a uniform dull grayish color; and on the evening of the 15th we encamped in the Mexican territory, on the left bank of Green river, sixty-nine miles from the South Pass, in longitude 110° 05′ 05′′, and latitude 41° 53′ 54′′, distant one thousand and thirty-one miles from the mouth of the Kanzas. This is the emigrant road to Oregon, which bears much to the southward, to avoid the mountains about the western heads of Green river, the Rio Verde of the Spaniards.'

Through this pass, as has been already said, all the overland emigration to Oregon passes, and almost all that to California. The emigrant route follows up the north fork of the Nebraska river from Fort Laramie, in order to pass the dividing line of the mountains at this favorable depression. This requires a course so far northerly as to make a considerable deflection in the route of those proceeding to California or Utah; and, in order, if possible, to find a more direct pass, Capt. Stansbury, in returning from the valley of the Great Salt Lake in 1850, made a reconnoissance of Bridger's Pass, which is so called after Major Bridger, who has charge of Fort Bridger, an Indian trading post on the Black Fork of the Green river. This pass is at the head waters of one of the northern tributaries of

the Grand river, called Muddy Creek, just above where it unites with St. Vrain's. Capt. Stansbury thus describes the crossing of the ridge at this point, indicating, also, his opinion that St. Vrain's will furnish a pass still better:

Sept. 20. Leaving the camp-ground early, we continued up the right bank of the Muddy Creek, over rather rough ground covered with sage, for a couple of miles, to within one mile of the point where the main fork comes in from the Park Mountains on the south-east, where it heads. Here we turned to the left up a beautiful pass about a mile and a half in length, with a uniform gentle ascent to its summit. From the top of this pass we continued for four miles over a gently undulating country, sloping to the right into the drainage of the Muddy. Here we reached the dividing height between the waters of the Atlantic and those of the Pacific.

“Before us lay an undulating country, descending gently to the east; beyond, in the distance, frowned the Medicinebow Butte, at the foot of which flowed the waters of the Platte, while to the southward of this famous headland stretched far away the Park Mountains, whence issue so many tributaries to the Pacific. From this important summit we commenced a scarcely perceptible descent into a wide grassy hollow, forming the valley of a now dry rivulet, which, in the spring, discharges its waters into Sage Creek, an affluent of the north fork of the Platte. Two miles east of the "divide" we halted to take a noon observation,

for latitude, which placed us in 41° 33′ 22′′.3, the computed longitude being 107° 30′ 48". Grass and water were scarce, and the growth of artemisia very thick, making it somewhat difficult to pass our little wagon over it. Near the mouth of this little stream, we crossed over to another, heading near to it, and running parallel with it, upon the banks of which we encamped, after a deeply interesting march of more than twenty-two miles.

"From what has been seen since crossing the summit, I am satisfied that it would have been better had we kept more to the southward before crossing it. If, leaving the ridge forming the southern boundary of the valley, we had followed either the stream upon which we are now encamped, or even the valley of another, some miles still farther south, we should not only have somewhat shortened our route, but obtained a greater abundance of grass, wood, and water, from a high ridge which bounds all these little streams on the south. Observations gave for latitude of the camp 41° 35′ 41", longitude 107° 21′ 32′′. Distance from Fort Bridger, two hundred and seven miles. With the exception of the rough ground near the head of the Muddy, which offers no obstruction of consequence, a perfectly feasible, and indeed a most excellent route, whether for a wagon or railroad, has thus been traced, presenting fewer obstacles to the construction of either than almost any tract of the same length in the country. The grades will be easy, the bridging comparatively light, and, with the exception of the crossing of

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the valley of the Muddy, where a long and heavy embankment may be required, the cuttings and fillings will be entirely within moderate limits. In no case will an inclined plane be required, and the route is more than usually free from the objection of high and narrow cañons, liable to be filled up or obstructed by snow during the winter."

There appears to be no depression in the mountain range south of Bridger's Pass, or of St. Vrain's Fork near it, which offers, even to the most sanguine, the idea of a route fit for a railroad, until about the parallel of 38°-north of the Spanish Peaks, but south of the high land around Pike's Peak. Col. Fremont suggests this region as the line for the projected line of railway; and the late Capt. Gunnison was directed to explore it by the government in 1853.

To come into the valley of the Del Norte, several mountain passes were in use by the muleteers; four of which were known as the Sangre del Christo Pass, the Roubidoux or Musca Pass, Williams's Pass, and the San Luis Pass. Once in the valley of the Del Norte, by one of these passes, the traveller has to get out again, and there are open to him westward the Coo-chi-tope Pass and the Leroux Pass. All of these passes were examined by Capt. Gunnison. The first four named proved quite useless for any purposes of a railroad; indeed, the "Sangre del Christo," which was improved as a supply road for Fort Massachusetts on the Del Norte, is but a difficult wagon road. Capt. Gunnison himself discovered a better summit level very low, over which