[twindman]

There is highway 14A on the west side of the Big Horns. There is a book for mountainous driving (East and West books). It calls this 14A as the 'Oh My God!' hill. It is 10 miles of 10% grade and 8 more of 8%!!!!! My wife won't let me drive it since our first trip on it in 2006 or 2007!
Not recommended to pull across Rocky Mtn Nat. Park. Also skip the highway out of Jacksonville, Wy west into Idaho. Pretty step and windy.


I would recommend you get the Mountainous Driving book too. It shows every main highway west of the Mississippi, I think. Listed by state and has a description of each section.