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SNOQUALME PASS. 
5. Railroad report of the practicability of the snoqualme pass, and the obstructions 
TO BE APPREHENDED FROM SNOW, BY MR. A. W. TINKHAM. 
[Mr. Tinkham extended the survey from the point to which it had been carried by Captain McClellan to Seattle, on Puget 
sound, and made examinations of the depth of snow in the month of January, 1854.] 
Washington, D. C., June 19, 1854. 
Sir: By your direction I made a winter examination of the line of the Yakima in January, 
and, crossing the mountains by the Snoqualme Pass, carried the line to Seattle, on Puget sound. 
The Columbia may be crossed near the mouth of the Snake river with a width of about four 
hundred and fifty yards. Crossing the Columbia, the line enters the valley of the Yakima. 
This river, in the lower part of its valley, has a width of some one hundred yards; flows with 
a steady current; is rarely fordable ; for about forty miles from its mouth has no wood on its banks, 
other than the small willow and occasional poplar; and is bordered on either side by high 
rounded hills destitute of woods, apparently dry, and scantily covered with grass, and on 
whose slopes the underlying trap-rock is frequently exposed. These hills, at several intervals, 
touch upon the river for a short distance only, and again retire frequently several miles from 
the river, thus dividing the river-bottom into several separate and prairie-like portions, to some or 
all of which the Indians have given names. The artemisia, in the part of the valley near the 
Columbia, is abundant on the more elevated positions of the bottom lands, growing less as we 
ascend the valley, and finally disappearing altogether. After ascending some forty miles up 
the river, portions of the bottom lands of considerable extent are noticed, so little raised above 
the level of the river as to be frequently overflowed and marshy; are marked by a stout, lofty 
swamp grass, and are cut with occasional slough-like channels, which are perhaps dry and hard 
in summer, but in winter were wet and miry, and were avoided by the Indians with me. 
For some one hundred miles up, the valley is extremely favorable; the rise of the valley is 
very small, (by Captain McClellan’s observations an average of but about twelve feet per mile,) 
and the only expensive work to be encountered being the limited amount of rock-cutting 
where the hills close in upon the river in three places of about ten miles in length, and one or 
perhaps two crossings of the Yakima, with several other small streams. At the end of this 
distance the valley narrows, and the more broken grounds show that one is on the slopes of the 
mountains. To Lake Kitchelus, however, within a few miles of the summit, the rise of the val¬ 
ley, though more rapid, is still very gentle. 
After the distance of forty miles spoken of as destitute of wood, the river is generally lined 
w r ith cotton-wood, the pine occasionally mingling with the lattfer wood, and becoming more 
numerous higher up the valley. 
By my own estimate the summit of the pass is one hundred and fifty-five miles from the 
mouth of the Yakima. At a distance of about one hundred and five miles from the mouth the 
line has entered the more open borders of the extensive wooded district, reaching thence to the 
shores of Puget sound. On the east slope of the mountains, pines, spruces, firs, cedars, larch, 
and some small amount of unimportant hard-wood trees, are the general growth; on the western 
slopes the mass of the growth is as elsewhere on the sound, fir and cedar. 
As might be supposed, the obstacle to be overcome in. this important route, presenting much 
that is promising, and demanding in the future surveys the most careful attention, is the passage 
of the summit with suitable grades. The saving of distance in the Great Trunk line, connecting 
the Mississippi and the great lakes with the Pacific, is so considerable as to warrant a large 
expenditure to overcome the natural obstacles of the route. 
Captain McClellan obtained barometric observations, giving a profile of the route from the 
mouth of the Yakima to a point three miles west of the summit. From this point westward, to 
the ocean, no connected observations have been made. 
To present clearly the result of my own observations, I will refer to the two methods suggested 
by Captain McClellan for passing the summit : 
