Phlox paniculata, which is listed as native to Ohio (though it is also used in horticulture, so I guess it depends on where you found it)
Using only this view how do we know it is not another, such as the P. carolina at the UBCBG garden plaza? Inflorescence structure?
I hinted at wanting to know where it was found -- whether it was a gardening situation or in the wild somewhere. That would help narrow the possibilities.