If you go out of Yellowstone s/b go to Bear Lake in Utah. It borders Idaho and Utah. Beautiful location. In Garden City Utah is a KOA that is a great place to stay. You have the lake across the street and many miles of quad trails to explore. You can continue s/b and go into Logan Utah to I 15. From there you head towards Salt Lake City and can take a side trip to Promontory Point. The spot where the rail roads met(east meets west). You get in for free is you have your National Parks Card.
Paul
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