When I took these photos yesterday, I was thinking this might be one of the Painted Lady (Vanessa sp.) butterflies. Then, as I took a closer look at the photos, I realized the wing pattern wasn't as close a match for that butterfly as I had initially believed it to be. So, I began looking through The Illustrated Encyclopedia of the Butterfly World by Paul Smart. Flipping through the color illustrations in this book is a real psychedelic trip, but I eventually found a match for this butterfly.
It could actually be either of two very closely related butterflies: the Hackberry Emperor (Asterocampa celtis) or the Empress Leilia (Asterocampa leilia). The adult of these two species look almost identical and they have an overlapping range with the Hackberry Emperor being more widespread. One of the primary differences between the two species is that the Hackberry Emperor caterpillars primarily eat hackberry leaves and the Empress Leilia caterpillars primarily eat elm leaves.
I really don't know what this butterfly ate as a caterpillar, but it appears to be a better match as an adult to the Empress Leilia. After all, that really doesn't matter. What matters is, it is a very beautiful butterfly:
