Asterocampa celtis is much smaller than our European Apatura but they share the same behaviour and habitat. They can be found in large numbers in some forested area (unlike our Apatura which are rather rare except in Far-East Russia).
North American Polygonia are very nice and much bigger than their European relatives. I had the pleasure to meet Polygonia faunus in Quebec 10 years ago, here is a very nice Polygonia progne from Indiana.
North eastern part of N.America is not as rich in butterflies species as western part is thanks to many different habitats ranging from high mountains to semi desserts. We have 24 Pieridae species in British Columbia but only 10 in Ontario.