This butterfly has markings are consistent with Canadian Tiger Swallowtail (Papilio canadensis), however, extrapolation of its size based on a typical size of 3" for a Common Milkweed flower head results in a wingspan of 4", making it much larger than the 3⅛" maximum wingspan for a Canadian Tiger Swallowtail.

Taken near the Water Towers at Prospect Park in Shrewsbury, Massachusetts on 8-July-2017. The location is the highest point in Shrewsbury (761 feet).