The meadow katydid Orchelimum superbum was previously known from scattered localities along the Atlantic and Gulf Coasts of North America. We found this species to be widespread and locally common on the Great Plains in a variety of habitats, including tallgrass prairie, wetlands, and roadsides. We found no evidence for cryptic species after studying the morphology of the male terminalia, comparing body size, and analyzing 14 calling song characters. Individuals from the Great Plains are consistently larger in body size than individuals from the historical range. From patterns of body size variation and abundance, we hypothesize that the eastern Great Plains is the center of distribution for O. superbum and that the coastal localities, including the type locality, are peripheral populations. We compare the songs of O. superbum and O. vulgare, showing that these two sympatric but allochronically separated species share most buzz-mode characters including statistically indistinguishable syllable repetition rates of 60 s^-1 at 25°C.