This line shapefile includes Global Map data showing the counties and equivalent entities of the United States, Puerto Rico, and the U.S. Virgin Islands. States and the national extent may be derived from the information included in the map layer. The data are a modified version of the National Atlas of the United States 1:1,000,000-Scale County Boundaries of the United States; that data set was created by extracting county polygon features from the CENSUS 2006 TIGER/Line files produced by the U.S. Census Bureau. This layer is part of the 1997-2014 edition of the National Atlas of the United States.Global Map data are part of a cooperative effort among national mapping organizations around the world to produce and maintain a standard set of basic cartographic data that supports global investigations of natural and human-built environments. Participating nations prepare data using a common data structure and description to ensure compatibility and to tangibly promote the tenets of the Global Spatial Data Infrastructure. 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 1:1,000,000-scale data. No responsibility is assumed by the National Atlas of the United States in the use of these data.