The data release for the geologic map of the Challis 1 x 2 degrees quadrangle, Idaho, 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 I-1819 (Fisher and others, 1992). The updated digital data present the attribute tables and geospatial features (points, lines and polygons) in the format that meets GeMS requirements. This data release presents the geologic map as shown on the plates and captured in geospatial data for the published map. 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 4.4 million acre, geologically complex Challis 1 x 2 degrees quadrangle, at a publication scale of 1:250,000. The map covers primarily Boise, Custer, Lemhi and Valley Counties, but also includes minor parts of Elmore County. These GIS data supersed ...