According to our slides, a Digital Raster Graphic is a 'scanned and georectified USGS topoquad.' The DRG is used as a base for other maps, and is tied into a datum. The above map is a portion of the Western Washington D.C. DRG, drawn between 1995 - 1998. DRG's like this one may be used as the basis for other maps, or to create 'hybrid' maps such as a combination of this DRG with a digital elevation map to create maps that accurately depict elevation or 'shaded-relief' maps.
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