Cimifuga sp.??

Too bad you didn't get a picture of the leaves. That would have helped alot in identification.

September is the wrong bloom time totally for Cimicifuga especially if it was in NY like your other pix. Flowers are wrong too. Rather than looking rather "hairy," you can see individual flowers with the Cimicifuga I'm familiar with. See link for Black Cohosh example. My black cohosh is in the process of turning from yellow to near black color, its fall leaf colors. I can only assume that is the reason for the common name.

Anyways, it originally struck me as being a Persicaria but I don't think that is right either.

FataMorgana

Here is a link that might be useful: Missouri Plants - Black Cohosh

I'd go with Cimicifuga/Actaea also. Most species ARE late season bloomers and depending on siting and climate, could bloom as late as October or upto first frost. Flower stalks look comparable to me - individual flowers are very tiny and do have a delicate, hairy appearance when open. A location in heavy shade would influence bloom time as well as the density of the individual flower stalks.

With the 'outbreak' of bed bugs throughout parts of the east coast, I'd expect Cimicifugas to become increasingly popular. The name is derived from the Latin cimex meaning 'bug', specifically Cimex lectularis (bed bugs) and fugare, meaning 'to drive away' and attests to this plant's insect repelling properties.

Here is a link that might be useful: Cimicifuga images

That is not Cimicifuga racemosa. Flowers are completely wrong.

I do have another (bad) photo which shows the full plant, but as a new member here I am not sure how to post it as a follow-up. I was photo-cataloging as a reminder to get back to take more photos in better lighting (and when the mosquitoes were not so fiercely on the hunt). Unfortunately I didn't get a chance to before the plants had been cut back for the season. I will post the other photo with new heading and see if that helps.

Sanguisorba, perhaps.