At eleven in the morning the train had reached the dividing ridge of the waters at Bridger Pass, seven thousand five hundred and twenty-four feet above the level of the sea, one of the highest points attained by the track in crossing the Rocky Mountains. After going about two hundred miles, the travellers at last found themselves on one of those vast plains which extend to the Atlantic, and which nature has made so propitious for laying the iron road.
On the declivity of the Atlantic basin the first streams, branches of the North Platte River, already appeared. The whole northern and eastern horizon was bounded by the immense semi-circular curtain which is formed by the southern portion of the Rocky Mountains, the highest being Laramie Peak. Between this and the railway extended vast plains, plentifully irrigated. On the right rose the lower spurs of the mountainous mass which extends southward to the sources of the Arkansas River, one of the great tributaries of the Missouri.