I am sure that anybody in the Southern US states knows that this plant with leaves of three is kudzu, not poison ivy.

However, if a northerner were to visit the south they would discover massive amounts of a vine with leaves of three – some with enormous leaves.

And the side two leaves are fatter at the bottom than at the top, just like poison ivy.

But this is kudzu, which might be as widely hated as poison ivy in the South, although for different reasons. The stuff really IS invasive and has taken over huge areas. 

Poison ivy is also all over the place, also a vine, but was here before humans, so technically not invasive.