Paulownia is blooming now. I wonder if that is what you are seeing?

Do the leaves look similar to marijuana?

If so, it's Vitex agnus castus, known as the Chaste Tree. It's a little early for it to be blooming though.

i second adele's guess of pawlonia (princess tree)- they are very conspicuous because of the size of the blooms and the fact the tree is bare or nearly so when it blooms. They are beautiful but invasive.

That was my first thought when I read the description as well (Royal Empress Paulownia). They have a few at the Arboretum in Hickory and they are the worst looking trees there because of storm damage. Apparently they are not extremely sturdy either.

I'm glad to know the formal name. I have a Chinese Royal
Emperess tree in my yard and it crossed my mind that it might be the op's tree. I also hear that they are invasive, but it is very pretty and it makes interesting large seed pods. I had one seedling grow to 10 feet from spring to fall.

It is on the invasive list. The wood is very light. At one point NCSU was growing some on an experimental plot near Reidsville to see if the wood could be used in place of tropical balsam wood.

Pretty, yes, but those big seed pods and fast growing aspects make it a prime candidate for the invasive list.

Of the 3 invasive trees that I see on the highways, it is interesting to note that different states seem to have different problems:

Georgia - Mimosa
North Carolina - Paulownia
Tennessee - Tree of Heaven

Of course all 3 are in all 3 states, but from a roadside point of view, I noticed these infestations vary from state to state in intensity.