Shuttle Radar Topography Mission DTED Level 2 (1 arc second) Data on DVD (United States and Territorial Islands)
SRTM DTED is a uniform matrix of elevation values indexed to specific points on the ground. The horizontal datum is the World Geodetic System 1984 (WGS84) and the vertical datum is mean sea level as determined by the WGS84 Earth Gravitational Model (EGM 96) geoid. The elevation data are with respect to the reflective surface, which may be vegetation, man-made features or bare earth. DTED Level 2 elevation values are spaced one arc second apart between 0 degrees and 50 degrees latitude, and spaced one arc second apart in latitude and two arc seconds apart in longitude between 50 degrees and 60 degrees latitude. SRTM DTED Level 1 values are derived from the SRTM DTED 2 values such that the DTED 1 values are identical to the DTED 2 values at coincident points. However, the SRTM DTED 1 values are spaced 3 arc seconds apart between 0 degrees and 50 degrees latitude, and spaced 3 arc seconds apart in latitude and 6 arc seconds apart in longitude between 50 degrees and 60 degrees latitude.
These data are now available on a cost recovery basis and can be ordered on CD-ROM for a mere $60 per CD
http://edcsns17.cr.usgs.gov/srtmdted2/
See also the level 1 – 3 arc second Global data product