Transportation
10
When automobile traffic made steep old wagon roads obsolete, a remarkable new highway grade was built down this hill in 1917. Designed as a gradual 10-mile, 2000-foot grade, it used a series of sharp curves that let cars travel 20 or 30 miles an hour, a good speed for that time. 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.
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Idaho · United States
