Data are included for two types of field surveys conducted for freshwater mussels throughout the Susquehanna River Basin (and one site in the Potomac River Basin) in the Mid-Atlantic region of the United States from 2008-2010. Timed search (qualitative) surveys were conducted in consecutive ~200 meter sections of river (at least 8 in each stream). The number of mussels of each species and associated search time were recorded for each survey section to determine a catch per unit effort (CPUE; number of individuals found per person hour). Within qualitatively surveyed areas, one ~200 meter section of stream was selected in which to conduct quantitative surveys to estimate mussel abundance, assess presence of juvenile mussels, and quantify population demographics. At each survey site, a subset of ~30 Elliptio complanata was haphazardly selected and retained for shell thin-sectioning and age determination. Two sites (Pine Creek and Buffalo Creek) were resurveyed both qualitatively and quantitatively in 2014 and 2015 after experimental re-introduction of the American eel (Anguilla rostrata), a documented host fish for E. complanata.