DRG

A DRG (digital raster graphic) is a scanned raster image of USGS 1;24,000 topographic maps, and can be used to collect, review, and revise digital data. This map is a portion of a digital raster graphic for Bushkill, PA.

URL: https://www.e-education.psu.edu/natureofgeoinfo/c6_p6.html