Thanks for asking a great question. I knew about Toxicodendron Rydbergii (Western Poison Ivy) but had assumed it was a western species like Toxicodendron Diversilobum (Western poison oak). Well wrong I was - this plant can be found in Ohio as well as in the top tier of states and the western states and eastern states south to North Carolina. Western poison ivy normally grows as a small shrub up to about 3' in height.
Here are a few links with additional info:
If you do a search on google for "Toxicodendron Rydbergii" you'll find more links. There are a number of sites which make only slight mention of this plant.
I'd love to see a picture of this plant.