Digital Raster Graphics

DRG is a digital copy of a USGS topographical map. They show 7.5 x 7.5 minute sections at 1:24,000 scale. This particualy map is one portrayed on the USGS website as an section of the map for the Washington DC Area. http://images.google.com/imgres?imgurl=http://erg.usgs.gov/isb/pubs/factsheets/fs08801.graphics/drg.jpg&imgrefurl=http://erg.usgs.gov/isb/pubs/factsheets/fs08801.html&h=310&w=386&sz=48&hl=en&start=2&sig2=uJ8m6x55c5DeKm1RgviFCQ&um=1&tbnid=hMCJU9OS73gweM:&tbnh=99&tbnw=123&ei=y4iXSNXeFZiCiAGirdWsCg&prev=/images%3Fq%3DDigital%2BRaster%2BGraphics%26um%3D1%26hl%3Den%26rlz%3D1T4GFRC_en___US219%26sa%3DN