Are these photos of Mountain Bluebells (Mertensia ciliata)? The first two are of the same plant in Custer National Forest. The third is of different plant, near Mount Rushmore, South Dakota. I think they are all the same flower, but I don't know enough to tell. All were shot in July.
I wouldn't guess it's P. speciosus - leaves look too wide. Someone who is very familiar with Penstemon IDs may be able to tell you what it is definitively from this photo. You can at least narrow it down to the species that occur in that area using USDA Plants and doing a state search, and then you may be able to narrow it down further based on a few obvious features.
