Eastern tiger swallowtails (Papilio glacus).
According to NABA-North Jersey Butterfly Club website, eastern tiger swallowtails are common in New Jersey.
They are attracted to purple coneflowers for nectaring, as shown here. Also wild bergamot and milkweed, which are also present in my garden. Larval food plants are black cherry and tuliptree. I don’t have either of these trees and don’t know if there are any in the area or not. Another butterfly website mentions magnolia, which I do have, as a larval food plant for eastern tiger swallowtails.
This eastern tiger swallowtail was much too busy to pay the least attention to me. Butterflies are not easy to photograph, even one so cooperative as this one. I was not able to get a spread-out pose. Still pretty awesome, don’t you think. Eastern tiger swallowtails on purple coneflowers.