National Elevation Dataset (NED)
2014
the u s geological survey has developed a national elevation database ned the ned is a seamless mosaic of best available elevation data the 7 5 minute elevation data for the conterminous united states are the primary initial source data in addition to the availability of complete 7 5 minute data efficient processing methods were developed to filter production artifacts in the existing data convert to the nad83 datum edge match and fill slivers of missing data at quadrangle seams one of the effects of the ned processing steps is a much improved base of elevation data for calculating slope and hydrologic derivatives