191 from Rock Springs Wy to West Yellowstone Mt.

I've driven all possible routes that I can find on my way to YNP/Tetons over the years if for no other reason than a change of scenery. North from I-80 as well as South from I-90. None are difficult drives, but like most areas in the western states, stop for gas around a half tank. The route north from I-80 via US 89 & US 189 is a beautiful drive along the Snake River on your way to Jackson, WY.