This U.S. Geological Survey (USGS) data release provides an updated digital geospatial database for the geologic map of the Dillon 1 x 2 degrees quadrangle, Idaho and Montana (Ruppel and others, 1993). Attribute tables and geospatial features (lines and polygons) conform to the Geologic Map Schema (USGS NCGMP, 2020) and represent the geologic map as published in USGS Miscellaneous Investigations Series Map I-1803-H (Ruppel and others, 1993). 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. References: 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/. U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020, GeMS (Geologic Map Schema) - A standard format for the digital publication of geologic maps: U.S. Geological Survey Techniques and Methods, book 11, chap. B10, 74 p., https://doi.org//10.3133/tm11B10.