Rhamnus cathartica (Common Buckthorn) is a well-established invasive species in North America. We searched early records of the species to help refine this species' history in North America. This note presents strong evidence of Common Buckthorn's entry to North America prior to the 19^th century and suggests it was originally imported for medicinal, not ornamental, purposes. We then briefly discuss aspects of its expansion across North America to about the mid-19^th century, when it was promoted as a hedge-forming plant. Such information is useful for reconstructing Common Buckthorn's invasion history (including reasons for its success), as well as for understanding human-invasive species interactions in general.