Looks like an Eastern Tiger Swallowtail (Papilio glaucus).

Here is a link that might be useful: Eastern Tiger Swallowtail

Good call, Northeastwisc. I have struggled with identification of the dark forms of the tiger swallowtail and the spicebush swallowtail. Now, I look for that row of yellow dots along the edge of the forewings of the dark tigers.

Thanks northeastwisc and serenoa. I also found the male version of the tiger swallowtail as well. Has been a good year for butterflies.