DRG- Denver, CO

DRG stands for digital raster graphic.  A DRG map like the one displayed above is a scan from the USGS series of topographic maps.  The scan displays all the cartographic information, as well as spatial data.  This is a DRG map of Denver, CO in 1899.  The newer USGS maps are much more detailed and most likely more accurate.http://www.ghostdepot.com/rg/maps/drg%20map%201899%20red.jpg