Anthropogenic environmental disturbances have decimated freshwater mussel populations across the US, so much so that they are now considered one of the country’s most endangered groups of animals. Preserved specimens located at the National Museum of Natural History (NMNH) are integral to understanding how US mussel diversity and distribution has changed across time and space, and thus are important resources for conservation stakeholders. Nonetheless, many specimens in the NMNH freshwater mussel collection are considered “problematic”, they do not align with our current understanding of US freshwater mussels biodiversity; for example, specimens may be misidentified, incorrectly georeferenced, or represent novel records that extend the geographic range of the species. Our objective here is to re-examine these potentially problematic specimens to confirm or revise their taxonomic or spatial information. Presently, we have re-examined 205 freshwater mussel records: 133 of these records have been determined to be misidentified, 37 of the records had inaccurate spatial information, 30 could not be reconciled given the available information, and 5 represent novel records that expand a species historical distribution. Revising the taxonomic and spatial information of these records revealed several previously unrecognized populations of endangered species. For instance, Plethobasus cyphyus, a federally endangered species, was previously unknown from Nebraska or much of the Missouri river subbasin, but these revised records confirm its historical presence in the area. Such records are foundational to understanding how distributions have changed across time and space and are critical to implementing effective taxon-based conservation efforts like the endangered species act.