This point shapefile depicts major dams in the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extracting dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, from the 79,777 dams in the U.S. Army Corps of Engineers National Inventory of Dams. This is a replacement for the April 1994 map layer. In the online National Atlas of the United States Map Maker, at scales smaller than 1:4,850,000 the data is thinned for display purposes. For scales between 1: 4,850,000 and 1:22,000,000, dams are only shown if they have a height of 500 feet or more, or a normal storage capacity of 50,000 acre-feet or more, or a maximum storage capacity of 250,000 acre-feet or more (1280 dams). At scales smaller than 1:22,000,000, dams are only shown if they have a height of 5,000 feet or more, or a normal storage capacity of 500,000 acre-feet or more, or a maximum storage capacity of 2,500,000 acre-feet or more (290 dams). Data of dams 50 feet or more in height, or with a normal storage capacity of 5,000 acre-feet or more, or with a maximum storage capacity of 25,000 acre-feet or more, is from the United States Army Corps of Engineers National Inventory of Dams and was compiled in 2006. This layer is part of the 2014 National Transportation Atlas Database. The National Transportation Atlas Databases 2014 (NTAD2014) is a set of nationwide geographic datasets of transportation facilities, transportation networks, associated infrastructure, and other political and administrative entities. These datasets include spatial information for transportation modal networks and intermodal terminals, as well as the re¬lated attribute information for these features. This data supports research, analysis, and decision-making across all transportation modes. It is most useful at the national level, but has major applications at regional, state and local scales throughout the transportation community. The data used to compile NTAD2014 was provided by our partners within the United States Department of Transportation (USDOT) and by other agencies throughout the United States Federal Government. These contributors are the actual data stewards and are ultimately responsible for the maintenance and accuracy of their data. This data is 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 in the use of these data. United States. Department of Transportation. Research and Innovative Technology Administration. (2014). Major Dams: United States and Territories, 2006. National Transportation Atlas Database 2014. Available at: http://purl.stanford.edu/vz228tt5490. In the online National Atlas of the United States Map Maker, at scales
smaller than 1:4,850,000 the data is thinned for display purposes. For
scales between 1: 4,850,000 and 1:22,000,000, dams are only shown if they
have a height of 500 feet or more, or a normal storage capacity of 50,000
acre-feet or more, or a maximum storage capacity of 250,000 acre-feet or
more (1280 dams). At scales smaller than 1:22,000,000, dams are only
shown if they have a height of 5000 feet or more, or a normal storage
capacity of 500,000 acre-feet or more, or a maximum storage capacity of
2,500,000 acre-feet or more (290 dams).