American ginseng (Panax quinquefolius L.) is a native North American forest herb whose roots have been collected for their reputed medicinal properties and exported to international markets for nearly 300 years. Numerous anecdotal reports suggest declining abundance throughout its range, and the species is currently listed in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora. This study examines the putative decline of American ginseng over the last 150 years in 19 US states by using data from herbarium specimens. For successive time intervals, we calculate the numbers of American ginseng specimens in addition to the numbers of specimens of related taxa that are not commercially harvested. The proportions of American ginseng specimens from adjacent time intervals are then examined for significant changes. An additional analysis evaluates the potential for species overrepresentation in the database due to species collection bias. Despite evidence of preferential collection of American ginseng, the proportion of American ginseng specimens declined significantly through time for six northern states. This result is consistent with a long and intense history of harvest, extensive deforestation in northern regions of the United States, and slow regeneration of American ginseng.