I had considered mourning cloak, but mourning cloak is supposed to have "eight red patches down the back". This image has 9 patches and they are more orange. Also, it appears there may be another row of patches down near the feet. Hard to tell for sure (from this angle), but look near the head.

I think this was a good guess. Can't tell the species for sure, but it should be either C. gorgone or C. lacinia. The larvae of these two species look almost identical, probably both occur in your area, and I'm not quite familiar enough with details to tell them apart (but I've reared lots of both). They both like to eat Composites such as Sunflowers, Black-eyed Susans, Iva, etc. Both species' caterpillars come in a mostly black form, a mostly orange form, and this form that is black with orange down the back (sometimes it is broken into spots, sometimes more of a solid orange band). I'm guessing that C. gorgone is more common where you took the picture?