DEM Files - Where to Get Them
More sources are listed at the bottom of this page.
USGS Seamless Data Distribution System has downloadable DEM files for the United States. The user interactively selects the desired coverage area and a DEM is constructed for that area (hence, "seamless"). Data are available from the National Elevation Dataset (NED), which is the "best available" DEM data. Shuttle Radar Topography Mission (SRTM) data are also available.
Make sure to select BIL or GridFloat format before downloading (they are not the default). Do this by clicking the "Modify Data Request" button before downloading. In the window that pops up, select BIL or GridFloat from the pop-up menu in the Data Format column. Then scroll to the bottom and click on "Save Changes and Return to Summary." (Other formats are available, but MacDEM only handles these two. The others are proprietary formats.)
The SDDS web site is picky about what browser you use. One person reports success using Netscape 7. I've been able to use IE 5 to select the coverage area, but the downloads fail, so I copy the URL from the download page into Netscape 4.75 to do the actual download.
USGS US GeoData has downloadable ASCII- and SDTS-format DEM files for the United States. Note that 1-degree DEMs are also called 1:250,000 DEMs, and 7.5-minute DEMs are also called 1:24,000 DEMs. I believe these scales refer to the scales of paper maps that cover the same areas, since the data in electronic form has no intrinsic scale.
If you know a latitude and longitude you can find the 1-degree DEM that covers it using the 1-Degree DEM file finder
NIMA Geospatial Engine has a map-based interface for accessing DTED Level 0 and image downloads. I was able to download DTED data using Mac OS 8.1 + Netscape 4.5.
DTED Level 1 (3 arcsec, ~100m) and Level 2 (1 arcsec, ~30m) data are
not publicly available.
California State University Northridge, Department of Geography has 7.5-minute DEM files for the western United States. For example, the state of California is accessible by name or by map, with an underlying directory structure grouped by degree. Files ending with ".CDO" appear to be MacBinary files. Use MacBinary or Stuffit Expander to convert them to usable form.
Geography Department of the University of Hawai`i at Manoa has DEM data for Hawaii including 1:24,000 data (look for elev.dem files)
Sea Floor Topography - go to "ftp digital gridded data", then download topo_8.2.img
University Earth System Science Center Database
Washington and Oregon State 10 m DEMs at the Regional Ecosystem Office
Yukon 90m DEMs at Yukon Renewable Resources