Yellowstone garters

[PINJOHN]

I have just been watching the autumn episode of YELLOWSTONE and it set me thinking as well as reminiscing about the place.
i visited the park a number of years ago with my two eldest sons who are not snake people so i did not get to do any herping,.... i am assuming that had i done so i might have come across parietalis is this correct and might i expect to have found any other species/sub/ ?

[Stefan-A]

Thamnophis elegans vagrans, Thamnophis sirtalis parietalis, Thamnophis sirtalis fitchi, Thamnophis radix. Possibly. Some other non-garter species as well.

[BUSHSNAKE]

fitchi would be the one you would find to be the most common