DRGs & Topographic Maps (FTP Link)
About Digital Raster Graphics (DRGs)
Digital raster graphic (DRGs) are scanned images (minimum resolution of 250 dots per inch) of USGS standard series topographic maps, including all collar information. The image is georeferenced and fit to the Universal Transverse Mercator projection. Most DRGs on this site are North American Datum (NAD) 1927_UTM_Zone11. Exceptions are the 1:24000 clipped/no collar files which are NAD 83 and the California DRG's which are NAD_1927_California_Teale_Albers. The USGS provides a free viewer you may download. For more information on DRGs go to the USGS DRG home page.