The Siskiyou Mountains run almost east and west, separating the Shasta Valley from the Medford Valley. Their crest conforms for that short distance, almost exactly with the boundary between Oregon and California. The railroad winds and twists in all manner of bends as it makes its roundabout way to the crest of the range. To one flying above the tracks, the curves seem unusually abrupt, but there is no other route for the tracks to follow in crossing the mountains. The only alternative is an exceedingly long tunnel through the base of the mountains. The expense of such a tunnel would be prohibitive on account of its great length, while the tunnel now used through the crest is really a very short one.