README file for digital data associated with: Weary, D.J., and Doctor, D.H., Karst in the United States of America: a digital map compilation and database: U.S. Geological Survey Open-file Report 2014-1156. There are two file packages available for download that contain the digital data for this map product. The compressed ‘USKarstMap.zip’ file contains GIS data in an ESRI file geodatabase format, and subdirectories files for displaying the map data in a GIS; each compressed subdirectory contains a README file specific to the contents of that subdirectory (see below). The ‘USKarstMap_KML.zip’ file contains compressed Keyhole Markup Language (.kmz) files of the karst and pseudokarst GIS data for display over digital globe applications such as Google Earth. Extracting the ‘USKarstMap.zip’ file results in a folder containing several files and subdirectories. The ESRI file geodatabase is named ‘USKarstMap.gdb’. The associated ArcMap document is named ‘USKarstMap.mxd’. The associated metadata file is named ‘Metadata_USKarstMap_FGDC.xml’. The subdirectories are: LayerFiles– This subdirectory contains ESRI layer files that were generated from the GIS software. These files may be opened into ArcMap version 10.0 or above to reflect the map unit cmyk colors assigned in the graphic representations in Open-file Report 2014-1156. These color definitions may also be imported into ArcMap when viewing the shapefile data to again match those in the publication graphics. Shapefiles– This subdirectory contains compressed ESRI shapefiles containing the GIS data for karst and pseudokarst areas of the United States, Puerto Rico, and the U.S. Virgin Islands. These data may be viewed, queried, and edited in ESRI and other GIS software. All of the GIS data and graphic representations are in Albers Equal-Area projection using the North American datum of 1983 (NAD83). Projection parameters for the contiguous United States are: Central Meridian: -96.000000; Standard Parallel 1: 25.000000; Standard Parallel 2: 50.000000; Latitude of Origin: 37.000000; Linear Unit: Meter Parameters for Alaska are: Central Meridian: -154.000000; Standard Parallel 1: 55.000000; Standard Parallel 2: 65.000000; Latitude of Origin: 50.000000; Linear Unit: Meter Parameters for Hawaii are: Central Meridian: -157.000000; Standard Parallel 1: 8.000000 Standard Parallel 2: 18.000000; Latitude of Origin: 13.000000; Linear Unit: Meter Parameters for Puerto Rico and the U.S. Virgin Islands are: Central Meridian: -66.500000; Standard Parallel 1: 8.000000; Standard Parallel 2: 18.000000; Latitude of Origin: 15.000000; Linear Unit: Meter