That one is the state flower, Mountain Laural.
Laural is mostly found on the tops of the mountains and the northern exposures, and Rhododendrons seem to like the damp bottom lands of the mountains along the stream edges.
In PA we also have hybrid rhododendrons in front of people's homes.
The Hybrid's bloom in the early spring along with the Azalea.
But the native Rhododendrons bloom Late June early July (after the Mountain Laural)
We to make it even more confusing, we also have native Azaleas in PA, but they call them Rhododendron Atlanticum, so I guess Azaleas and Rhododendrons are related
Anyway, how many "other" types of "bikers" stop and look at the flowers