http://www.mrlc.gov/viewerjs/ has a map view and the ability to subset small regions instead of the tiles you get at the National Map. This can avoid having to merge the data.
Zoom in the to area desired. The map can be resistant to dragging the viewport; just be persistent.
Open the download tool in the upper right of the map.
Pick the NLCD data you want, and optionally NED. The most useful data is the "Land Cover", for which you would like the 1992, 2001, 2006, and 2011 coverages. Much less useful for the Forest Canopy and Impervious Surface.
Pick one of the two tools to either outline the area you want, or to enter keyboard coordinates. Get extra. You can easily subset the coverage area later, but if you don't get enough, you have to redownload. These are a conic projection and the web site might not be smart enough to cover your entire box.
|If the data is in the correct format (you would prefer GeoTiff), pick the "Download button".
Otherwise pick Modify Data Request. If the program will not let
you modify the format for NED, you can get the ArcGRID. You will
GDAL/, and will have to select the "w001001.adf" file in the
If you have multiple tiles per layer, pick Modify Data Request to increase the maximum size per tile ("piece") if it will let you; this might be a hint to pick the 1" NED instead of the 1/3".
It will take some time for your data to be extracted. If you cannot do this, you will have to merge the files, which should be possible for the DEM but might not be easy for the NLCD, and you should get a smaller area.
You must keep track of where to save it, and being able to determine which data set it is. The file names for the ZIP, and the extract, is a random string of numbers. The files should start with LC92, LC01, LC06, and LC11, for Land Cover and the last two digits of the year.
Insure the program can
recognize the NLCD data set.
Last revision 9/52/2018