I cannot agree with Mr. Neihardt that the Mississippi obliterates the Missouri within a few hundred yards, or even a few hundred miles; for in all but name it is the latter, not the former, that mingles its mud with the Gulf of Mexico. But in his contention that the Yellowstone is the dominant stream where it joins the Missouri he is borne out by all that I saw and the opinion of every authority I talked with, from a half-breed river-rat at Buford to the Army engineers at Kansas City. My third reason for choosing the Yellowstone was the technical consideration of superior "boatability." The head of continuous small-boat navigation on the Yellowstone is about at the northern boundary of the Park, at an elevation of over five thousand feet. On the Missouri it is at Fort Benton, below the cataracts of Great Falls, whose elevation is less than half that of Gardiner. As the distance from these respective points to the junction of the two rivers near the Montana-North Dakota line is about the same, it is evident that the rate of fall of the Yellowstone is many times greater than that of the Upper Missouri below Benton. Indeed, the figures are, roughly, 3000 feet fall for the former and 500 for the latter. This means that the Yellowstone is much the swifter stream and, being also of considerably greater volume, is infinitely preferable to the boatman who does not mind more or less continuous white water. In addition to these points, the fact that the Yellowstone, from the Park to its mouth, flows through one of the most beautiful valleys in America while the Missouri meanders a considerable distance among the Bad Lands, makes the former route the pleasanter as well as the swifter one. These considerations, pretty well in my mind before I started, were more than borne out in every respect by my subsequent experience. There are two or three large rivers down which boats (by frequent linings and portagings) can be taken which are of greater fall than the Yellowstone, but I know of none anywhere in the world on which such fast time can be made as on the latter--this because its rapids are all runnable. As I was not out for records of any description upon this trip, it was no part of my plan to start from the remotest source of the Yellowstone, some twenty-five miles south of the southern boundary of the Park, but rather simply to follow down from the most convenient point where the Continental Divide tilted to that river's upper water-shed. Following the river as closely as might be by foot through the Park, it was then my purpose to take train to Livingston and resume my voyage from about where it had been abandoned two decades previously. As the steel skiff I had ordered was extremely light, and of a type quite new to me, I did not care to make my trial run through "Yankee Jim's Canyon."