This polygon shapefile portrays the time zones of the United States, Puerto Rico, and the U.S. Virgin Islands. Also included are the Greenwich Mean Time offset, and areas in the U.S. where daylight saving time is observed. This is a revised version of the September 2004 map layer. This layer is part of the 1997-2014 edition of the National Atlas of the United States. These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National Atlas of the United States or the U.S. Geological Survey in the use of these data. None. Acknowledgment of the National Atlas of the United States of America and (or) the U.S. Geological Survey would be appreciated in products derived from these data. This layer is presented in the WGS84 coordinate system for web display purposes. Downloadable data are provided in native coordinate system or projection.