This is Hesperis matronalis, a member of the mustard family. Not native phlox, though I knew it as phlox for the first 40 years of my life. Hesperis matronalis, an “invasive species” that has been around here for a long time, though not quite as long as many other invasives, such as Homo sapiens. These are on Rte. 80, just east of Sherburne Village. Bob Smith’s back yard. Tons of them along the river. Gorgeous.