The data release for the geologic map of the Dillon 1 x 2 degrees quadrangle, Idaho and Montana, is a Geologic Map Schema (GeMS)-compliant version that updates the GIS files for the geologic map published in U.S. Geological Survey (USGS) Miscellaneous Investigations Series Map I-1803-H (Ruppel and others, 1993). The updated digital data present the attribute tables and geospatial features (lines and polygons) in the format that meets GeMS requirements. This data release presents the geospatial data for the geologic map that is published as one plate. Minor errors, such as mistakes in line decoration or differences between the digital data and the map image, are corrected in this version. The database represents the geology for the 4.3 million acre, geologically complex Dillon 1 x 2 degrees quadrangle, at a publication scale of 1:250,000. The map covers primarily Beaverhead, Madison, Silver Bow, Deer Lodge, and Lemhi Counties, but also includes minor parts of Ravalli, Granite, and Jefferson Counties. These GIS data supersede those in the interpretive report: Ruppel, E.T., O'Neill, J.M., and Lopez, D.A., 1993, Geologic map of the Dillon 1 x 2 degrees quadrangle, Idaho and Montana: U.S. Geological Survey Miscellaneous Investigations Series Map I-1803-H, scale 1:250,000, https://pubs.usgs.gov/imap/i-1803-h/.