National Elevation Dataset
The National Elevation Dataset consists of high precision ground surface elevation data for the United States. It was maintained by the USGS and all the data is in the public domain. Since the 3D Elevation Program came online, the NED was subsumed into The National Map as one of its layers of information.Formats
Data is available in a few popular formats such as ESRI ArcGRID, GeoTIFF, BIL, GridFloat, and a few others.Precision
Depending on area location, the datasets are provided with 1/9, 1/3 and 1-arcsecond precision.
