Cutting the bark like that might slow down the growth, BUT it would also make the trees very dangerous as the wood would start to decay, leaving the trees liable to fall in a storm. Definitely not recommended.

Resin

I agree, stripping the bark would leave them weakened and highly liable to be blown over in a storm and probably damaging your or your neighbor's house. In short there is no way to slow a tree's growth, other than killing it, for all practical purposes.

Here's one way:

Here is a link that might be useful: Growth Retardants

There are also other ways, but the ones I'm thinking of would be very difficult to undertake on a tree as large as the one you are talking about.

"They have grown "up" more than "out" and are tall and skinny."
That's right, that's the way a Black Locust grows, I've never seen one that wasn't fast growing, tall & skinny. Sounds like your trees are just doing what Black locusts do.
Sam

Thanks brandon7 for the link...unfortunatley my webtv can't access it. And thanks to all.

I had been told by a local "garden hotline" that commercial fruit growers often had to remove bark to get trees to stop growing and produce fruit instead.

I was hoping someone on the GW had actually tried this. Looks like I'll be the first. I'll have to remove the trees eventually...I just didn't want to do it this year. So I'm going to go ahead and remove some bark, all the while keeping m fingers crossed! I'll post results later this summer.

I think the good news is that these are strong trees and don't present a hazard. And if you burn wood there's hardly anything better. Mebbe also true that they have been going through an adolescent phase and will slow down on their own now?

Our neighbor's boulevard has two of them, and they can be beautiful, if late to leaf out. He doesn't like them but my wife in particular admires them. They do send out lots of shoots, though.

warko,
I wouldn't advise the girdling thing that's been suggested to you.
I have, however, done 'bark inversion' on a few apples & pecans - cutting & removing a 1-inch wide strip of bark, turning it upside down, and replacing it, then wrapping as if you had performed a graft there.
It's an ancient technique for dwarfing and speeding up time to flowering/fruiting, similar to 'looping', tying an overhand knot in the trunk of a limber seedling.
The inverted section of bark will callus in, and since it is in an abnormal orientation, it will retard, to some degree, the flow of nutrients/auxins produced in the portion of the tree above the inversion for a period of time - I've seen claims of up to 4 years, after which you have to invert another strip, if you care to continue the dwarfing effect - and it also seems to speed time to flowering/fruiting, which can often be quite lengthy for seedlings.
Another downside: you usually end up with a not-especially-pretty 'lump' in the trunk at the site of the bark inversion, and the potential is always there for a failure of callusing, resulting in death of the portion of the tree above the inversion.

lucky_p, I'm not clear about the "1 inch-wide inch strip". Should I remove a 1" wide strip around the entire circumfrence of the tree and invert it? Or did you mean something else? Details, please.

I will try your method first. Thanks very much!

Maybe that terrible line of storms will knock a few branches off the trees for ya?

Yes.
Bark inversion entails making two complete circumferential cuts, approximately one inch apart, making one vertical cut to connect the two circumferential cuts, lifting that strip of bark, turning it upside down and putting it back into place, then wrapping with appropriate material(Parafilm, grafting rubbers or rubberized electrician's splicing tape, etc.) - just as you would if you were performing a graft.
Google "Bark Inversion" for more info, or email me direct - I have an article on bark inversion I can forward as an attachment.

If you can't afford tree removal, Maybe you could afford just getting them topped? All the bark cutting would make me very nervous that I'd wind up with sick and/or dead/dying trees. The bark inversion sounds fascinating, but also like an expert should do it??? Otherwise you'd just be ringing it and killing it, and REALLY wishing it hadn't fallen on your neighbors house :P since that would be your fault, not an act of nature.

"Maybe you could afford just getting them topped?"

Very bad idea, and would cost just as much (if not more, as more climbing work is involved) than having the trees removed altogether.

Resin

lucky_p, thanks again, I will google "bark inversion"...my webtv may not be able to access your attachment, as is often the case.

And thanks to everyone who responded. I'm going to do the bark inversion and if the trees starts dying, at least I will have plenty of time to make arrangements to have them removed. Black locusts are a very hardy tree, I know because I have others in my yard that I let grow for quick shade.

I'll post my results later.

I threw the bark inversion technique out as more desirable than your original plan to just girdle them.
Still, I wouldn't be inclined to do *either* on two-story tall trees within falling distance of my home.
You +probably just need to bite the bullet and have them removed - and then deal with root suckers that will be popping up all over your yard for the next few years - or choose some of them to become 'new' trees - they'll be tall before you know it.

I'd strongly advise against trying the bark inversion technique; although fine in theory, in practice it needs extremely good technical expertise to carry out. For starters, the band of bark has to be exactly the same width all the way round (to within a millimetre), or it won't fit back into the cut after inverting. And also Black Locust has much thicker, less flexible bark than fruit trees do, but also tend not to have neat circular trunks. The inverted piece won't be the same shape as the cut but a mirror image of it, and won't be flexible enough to bend into the right shape. The chances of success are close to zero.

Resin

I suspect you're correct, Resin.
I've only done bark inversion on young apples & pecans, both still quite smooth-barked, with trunk calipers of less than 3-4 inches.
Dr. Saks, who pioneered the technique at Morton(or was it Arnold?) Aboretum, did do it on larger specimens, but again, he'd probably done it many times on smaller trees, and had quite a bit of experience/expertise in the technique.