Natural history museum records may provide unique information on the distribution of species that can supplement survey data collected by resource managers. However, there can be challenges to using museum data for analyses, such as spurious geographic information, misidentifications, and incorrect labeling. Museum records have been centralized by open-source repositories with flags for coordinate precision and out-of-range specimens, providing some information about record uncertainty in general. Verification of uncertain museum records could increase confidence in distribution data and improve understanding of biodiversity patterns and range dynamics through time. The goal of this study was to determine if museum records provide unique information about the distribution of the Yellow Lampmussel Lampsilis cariosa (Say, 1817), an at-risk freshwater mussel species. We created a dichotomous key based on a hierarchy of conchological characteristics to verify the taxonomic identity of flagged L. cariosa specimens and assessed records occurring outside of the species’ expected range as compiled from primary literature. Fifty percent of flagged specimens were confirmed as L. cariosa. Of the invalid records, 56% were misidentifications, mainly of other Lampsilis species. Overall, museum collections (1800s–present) contributed 32 unique watersheds not represented by modern survey records (1980s–present, comprising 92 watersheds) including 13 unexpected watersheds in regions of New York and Vermont (USA) and Québec and Ontario (Canada). Our study provides a reproducible method for the reverification of freshwater mussel museum records and highlights how these records can provide unique contributions to our understanding of the geographic range of a rare, at-risk mussel species.