Eupatorium.

It is usually useful to have photos of the whole plant from the side as well as close ups of leaves along with the flowers.

Some types of Joe Pye weed are now classified in the genus Eutrochium though it used to be Eupatorium. I can’t see enough of the plant’s other details to tell which this is.

NHBabs, yes, I think you are right. I do try to get the leaves, but this time I neglected.

This gives an introduction to what's involved with this group:

http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=112351

Note that 24 species are recognized in North America, just for Eupatorium sensu strictu.