When automobile traffic made steep old wagon roads obsolete, a remarkable new highway grade was built down this hill in 1917.
With a series of sharp curves that let cars go 20 or 30 miles an hour - a good speed for that time - a gradual 10 mile, 2000 foot grade was designed. It still can be used by anyone not in too much of a hurry who wants to see an engineering model of early highway construction.
All, of which, of course, makes it a wonderful motorcycle road, though the speeds suggested above are a bit pessimistic. We also saw bicycle riders going down the hill!
On a different tack, Lewiston is a "sea port", as explained by another sign at the top of the Spiral Highway:
Steamboats started May 13, 1861. As a steamboat landing, Lewiston immediately became a primary commercial center for Idaho miners during their hectic gold rush to Pierce that spring.
Steamboats continued to dock there until 1940, mainly after Columbia and Snake River channel improvements made navigation practical in 1914. Finally, a series of locks and dams made Lewiston a seaport, and large scale river shipping resumed in 1975.
The far right view of the road.
Centre view.
Left view (overlaps quite a bit with centre view).
Enjoying a break at the top - from the left: Brian, Dave, Roger, Mark and Corey.
Boggan's Oasis