Original Product Resolution (OPR) Source Digital Elevation Models (DEMs) - USGS National Map 3DEP
          Downloadable Data Collection
This data collection is the Original Product Resolution (OPR) Digital Elevation
        Model (DEM) as provided to the USGS. This source DEM is delivered in the original resolution, units and horizontal and vertical spatial references. These
        data may be used as the source of updates to the 3D Elevation Program …