The area of study is restricted to the northern Appalachian region between latitudes 38N and 48N and longitudes 66W and 77W in the U.S. states of Maine, New Hampshire, Vermont, New York, Massachusetts, Connecticut, Rhode Island, Pennsylvania, and Delaware. This study (Wintzer and others, 2025) integrates data from several sources, including geologic, geochemical, geophysical, watershed analysis, and mineral sites with recently developed grade and tonnage models, expert estimates, and software tools and analyses to generate probabilistic estimates of undiscovered lithium pegmatite resources. These data are presented in several formats: shapefiles, and tabular (csv) data. Several layers or individual files are derived or contain data from U.S. Geological Survey (USGS) and other existing, published sources.