Rocky - I've been to Horseshoe Bend >>>steep uphill in a work truck towing a trailer.
Coasting down it you could probably go 100mph.
I do not understand why one would pass through HSB en-route from Boise to Id 95.
Yes Whitebird and Lewiston Hills were both MFers before they were rebuilt. More so with snow pack. I saw the new road being built at Whitebird in about 1973 while we were traversing the switchbacks in a Chrysler town and Country wagon w/ a 440 loaded full of people and gear pulling a twenty foot RV. We were on the way to Elk City for a Sheep hunt.
My Uncle used to run from Treasure Valley to N Idaho once or twice a week pulling mobile homes in the sixties and seventies. His wife drove pilot car for him. She would have to drive to the top of the hill and stop all traffic while he negotiated the switchbacks with a 12x60 foot trailer. I can not even imagine.
