This checklist is offered to fulfill an immediate need in North American lichenology: a floristic summary interpreting the published records in the light of recent taxonomic and no menclatural research. That such a summary is long overdue is shown in that 2,280 species in 193 genera are listed below as compared to some 1500 species in Fink’s 1935 Lichen Flora of the United States. Since our list is largely compiled from many published articles, necessarily of unequal quality, some inclusions are incorrect, some exclusions unjustified, and some oversights inevitable. But the very shortcomings of this list should stimulate further study.