A little below the junction it empties into the Bitter Root, which, after a winding course of a hundred miles, is joined by the Flathead, that comes down from Flathead Lake and the country around Marias Pass. The united streams below the junction take the name of Clark's River, which has a circuitous course northward, running for a little distance into British America, then back again through a wide plain till joined by the Snake, and the two become the Columbia, pouring a mighty flood westward to the ocean. The line of the road does not follow the river to the boundary between the United States and the British Possessions, but strikes across the plain of the Columbia. The characteristics of Clark's River and the surrounding country are thus described by Mr. Roberts:-- "Clark's River has a flow in low water at least six times greater than the low-water flow of the Ohio River between Pittsburg and Wheeling; and while its fall is slight, considered with reference to railroad grades, it is so considerable as to afford a great number of water-powers, whose future value must be very great,--an average of eleven feet per mile. "Around Lake Pend d'Oreille, and for some miles westward, and all along Clark's River above the lake as far as we traversed it, there is a magnificent region of pine, cypress, hemlock, tamarack, and cedar timber, many of the trees of prodigious size. I measured one which was thirty-four feet in circumference, and a number that were over twenty-seven feet, and saw hundreds, as we passed along, that were from twenty to twenty-five feet in circumference, and from two hundred to two hundred and fifty feet high. A number of valleys containing large bodies of this character of timber enter Clark's River from both sides, and the soil of these valleys is very rich. Clark's River Valley itself is for much of the distance confined by very high hills approaching near to the stream in many places; but there are sufficient sites for cities and farms adjacent to water-powers of the first class, and not many years can elapse after the opening of a railroad through this valley till it will exhibit a combination of industries and population analogous to those which now mark the Lehigh, the Schuylkill, the Susquehanna, and the Pomroy region of the Ohio River. Passing along its quiet scenes of to-day, we can see in the near future the vast change which the enterprise of man will bring. That which was once the work of half a century is now the product of three or four years. Indeed, in a single year after the route of this Northern Pacific Railroad shall have been determined, and the work fairly begun, all this region, now so calm and undisturbed, will be teeming with life instilled into it by hardy pioneers from the Atlantic and from the Pacific.