I have a couple pretty good sized black locusts on the property, but nothing close to this one. It ended up being pretty punky, and ants had hollowed out the butt end, but still was some good wood in there. Came from a pasture field and was dropped off at my buddy's place.
There's a couple places within ten miles of me that must have had black locusts planted sometime early in the last century. Alongside old farm roads, I guess. There are straight rows of evenly spaced locusts and most of them are at least 30" in diameter. A friend of mine had a 44" diameter locust log dropped off in his yard by a tree service about 10 years ago and it's still sitting there. I will try to get some pictures. That's still a good-sized tree though.
Around here a good portion of the older homes have them. We're talking 1700 mid 1800 houses. They all have 40+ inch black locust. They are taller than anything else too. Really surprised to see any punk in it.
Wow! Perhaps it's my local climate? Rarely do you see one live past about 14-15" around here. Had a real nice one that had been topped for posts a couple times in my lifetime that gave up the goat in the 2011 windstorm down on the river lot. Never noticed how much shade it threw until it was gone. It was about 24-26" DBH. I've got my eye on a couple of typical ones by the creek bottom. They are still alive...barely. Big old trees with half dozen small branches producing leaves way up top. Those locusts are Tough I tell ya.
They do get used for posts still in these parts. I have had a couple people be surprised by few 20" or so that I have still standing. Both have had their tops blown out and are ugly as sin, but still alive. They really are pretty decent trees. Pretty in the spring and they don't make much of a mess with branches or leaves.
I have a couple at my workplace that are pretty big. One is probably 24" DBH and hollow, the other is close to 3' at the base and has several trunks/branches starting about 4' off the ground. Will take some photos tomorrow before dark.