Penstemon haydenii (blowout penstemon) is a federally listed endangered species, endemic to sand dune blowouts of the Ferris Dunes of Wyoming and the Sandhills region of Nebraska. These two populations are separated by 175 miles. Given the disjunct nature, the recent discovery of the Wyoming populations of this narrow endemic, and reported morphological differences between Nebraska and Wyoming populations, we investigated the phylogeographic history of the species using demographic modeling, species delimitation, and species distribution modelling approaches.