How does one view the data in GIS applications?
ESRI’s ArcGIS does not allow the user to view the data natively – it must be imported first. To import the .DEM files to a format compatible with ArcGIS use the “DEM to Raster” tool available in through “Conversion Tools” section of ArcToolbox. The data are floating point, so verify that the data type is set to “FLOAT.” Other GIS applications may read the USGS DEM format natively, or they require that the data is imported prior to use – check the application’s online help for guidance on utilizing USGS DEM formatted data.