Dave,
I don't define it is an invasive. Here in the East, to have one in your yard is a rarity because the climate perhaps is unsuitable for the pervasive spreading of the species. I have never noticed seedlings either existing much less taking root. That quality of "taking over" is not an issue here.
50 years ago, I would visit my Grandmother on the coast of Connecticut and she had one on either side of her front door and would nurture them fearing that the next winter freeze would do them in.
I suppose invasive can be a synonym for "not indigenous". Clearly Mimosas are not indigenous to inland Connecticut. Now if we could do something about the Starlings, House Sparrows, Barberries and so many others which truly are a worrisome infestation and have taken root and spread like the plague. Is the Mimosa defined as such where you live?
Thanks for bringing up this issue. Knowing that it was an exotic has up-to-now appealed to me. I will now view this tree in a somewhat different light. By the way, the tree was here when we moved into this house 14 years ago. Perhaps it has the tenacity of a true invasive after all. It is simply waiting for the climate to change another degree or two in its favor and then it will take over. Egad, seeds do fly however beautiful or vexing their progeny might be!
Cheers,
Tom
added edit:
I have done some research after writing my first note to you. It appears that invasive is a correct description of the Mimosa. When our next winter storm crushingly demasts it as happened a few years ago, I may just take it down for good even though it is "deceptively pretty".