The National Elevation Dataset (NED) is the primary elevation data product produced and distributed by the USGS in partnership with the National Geospatial Program. It provides seamless raster elevation data of the conterminous United States, Alaska, Hawaii, and the island territories. Data are available at grid spacings of 1- and 1/3-arc-second (about 30 meters and 10 metesr respectively) for the conterminous United States, and 1/9-arc-second (about 3 meters) for parts of the United States.
Lidar data, from Federal, State, local governments, and private sector providers, have become the primary source data of the NED. In FY 2012, the incorporation of high-quality lidar DEMS into the NED resulted in an additional 233,288 square miles of high-resolution, bare-earth elevation data.
NED is revised bi-monthly to integrate newly available and improved elevation source data. High resolution lidar DEMs are incorporated into the 1/9-arc-second NED and also into many of the lower resolution NED layers. In FY 2012, 196,261 square miles of high-resolution data were incorporated into the NED 1- and 1/3-arc-second data layers. The August update marked the 67th update of the NED bi-monthly revisions since June 2000.
U.S. Geological Survey's National Elevation Dataset high resolution elevation inventory and status.