On April 3, 2018, the U.S. Fish and Wildlife Service (Service) published a final to rule listing the yellow lance mussel (Elliptio lanceolata) as threatened under the Endangered Species Act (ESA). The final rule states that only seven populations of this freshwater mussel remain, all of which are located in Maryland, Virginia, and North Carolina. The listing was prompted by a “mega-petition” filed by the Center for Biological Diversity and several other environmental organizations in 2010 that included the mussel. In September 2015, after litigation had been filed regarding the petition, the Service entered into a stipulated settlement obligating the Service to make listing decisions about the species in the petition by a specific deadline. With respect to the mussel, the Service specifically agreed to submit its proposed finding on whether or not to list the mussel by no later than March 31, 2017. The final rule identifies urbanization and the effects of climate change as threats to the mussel, which contribute to habitat loss and degradation. The Service did not include an ESA section 4(d) rule in its listing decision, but stated that it plans to propose a 4(d) rule regarding permissible incidental take in the future. The final rule indicates that a careful assessment of the economic impacts of the mussel’s listing and potential critical habitat is ongoing, and that a proposed rule to designate critical habitat will be published in the near future.