Driving Through Idaho: Seeking Insight

[Fish Taco64]

I wouldn't advise speeding significantly, for several reasons (Wisconsin transplant here, so I am quite familiar with driving habits in the upper midwest).

There is not as much traffic, so your 9mph over is much more likely to stand out to a trooper on the side of the road. Throw in out of state plates and you might as well write the ticket yourself.

On the back roads, especially closer to Yellowstone, the road can be curvy, hilly, and home to conditions that you just don't see in the midwest. At those elevations, there is always a chance of ice patches or slick spots, regardless of the time of year. You also don't want to take a sharp curve at 8 mph to find a moose waiting for you on the other side of it.

The road between SLC and Yellowstone is often occupied by tourists that are distracted, or inexperienced in the type of conditions they can encounter here. Speeding reduces the time you have to react to mistakes hy these drivers.

I strongly recommend the Mesa Falls scenic byway, it is well worth it and does not add much time to your trip.

[Clark Fork Fantast]

I've answered the OP's similar question over in the WY Forum, so I'll just add my 2 cents' worth here: Speeding will increase the likelihood of hitting wild animals. Especially around sunset, but any time of the day or night, really, there will be deer trying to cross the rural roads (and sometimes even in the small towns). Hit a deer, or an elk, or a moose, and it will impact your vacation in a major way... And that can happen driving at the speed limit or even under, but the likelihood of a worse accident is much higher if you speed.