what is this prolific vining plant?
This looks like it might be a clematis plant. It looks like it is developing buds. If you would like to send us additional photos of the flowers when it blooms, we would be happy to take another look.
Wish I got a better shot of the white blooms. But here they are. Not a super beautiful bloom like cultivated clematis. But the leaves don't look like a native clematis either, right? It's kind of taking over!
The actual flowering part is not in clear focus, but it looks to us that the plant is still in bud and the flowers are not open yet....
Could you try to get a photo of the flowers themselves?
We are fairly certain this is a type of clematis, and likely a non-native invasive.
Did you notice if the vine was evergreen, with leaves remaining in the winter?
Given that it's threatening to "take over" it may not be a bad idea to pull it out. Invasives get the advantage over native plants by being able to grow faster, cover more ground, and by blooming and setting copious amounts of seeds, and you don't want more of them.
I'll try to get another photo later. But to answer your question about evergreen leaves, these leaves were definitely NOT evergreen in the winter. It died almost completely back. I wasn't sure if it was going to return in the spring.