Going north from West Yellowstone (Henry's Lake State Park)

[SailorSam20500]

Looking to get up to Great Falls from Henry's Lake state park near West Yellowstone during the first week of October. Looking at either 191 or 87/287 to get up to I-90.

Flattest Route depending on which cities I use shows either a couple of >20% grades or a lot of even larger grades.
87/287 shows two ~15% grades.
191 according to Rand McNally is a scenic route.

So, my question is, what are these two routes really like? Should I be considering something else?

[jbflag21ds]

191 is currently getting repaved just north of the park so it should be a nice drive pending weather. I just drove it last week and have the rocks and asphalt on my truck as a souvenir, ugh. Lots of turn outs along the river in the wider parts of the valley. Pretty this time of year.

I much prefer 87/287 to 90 regardless just due to it being mostly flat and fewer curves. Plus there is cell coverage unlike being in the valley on 191. If you enjoy "big sky country" type views, this is the route for that in that area.