Most users know about it (or should know about it), therefore, as a result it sometimes gets forgotten. Think of the seamless data distribution system as the grand-daddy of the USGS geospatial repositories… and then some! This site has complete coverage of the National Elevation Dataset that supercedes Digital Elevation Models, complete DOQQ coverage, over 30 TB of urban imagery, one-time coverage of full resolution Landsat imagery, and much more. Also, the data are seamless, so you can put a box around the data without having to figure out quadrangles and then having to assemble them all. Free downloads are available – up to 1.6 Gbytes of data in 100 MB files in one user request. Users have unlimited access to the interactive map and can make unlimited requests.The amount of coverage area depends on the number of products selected for download. For example, if NED 1 Arc Second is selected as the only product a user can download up to a 30 square degree area. Most recently Additional data formats are now available for all High Resolution Orthoimagery products See http://seamless.usgs.gov/