Looks like one of the Clematis species to me that often smother railway banks etc over in the UK and is often referred to as "old mans beard" They spread like wildfire from seed and can be an absolute swine to pull out.

Yep, looks very much like C. vitalba. Not native to USA, but has been introduced and is now classed as a pest because of its invasiveness.

Thanks you

Looking at this again I wonder if it is C fargesii rather than C. vitalba? Depends to a certain extent on how big the flowers are, fargesi flowers are very much bigger.

thank you so much for trying to figure this out. I know it's not easy. The flowers are approximately 2 inches in diameter.

Then fargesii is more likely than vitalba. Cannot find out if that has been introduced into the USA though. Perhaps you could Google it and see?

It does seem peculiar - seems a little out of place too. It's extremely tenacious, I will Google it and thanks again.

Paul :)