According to the USGS, their maps have been downloaded by the millions since converting to digital delivery. The U.S. Geological Survey, through the National Geospatial Program, has delivered more than 18 million US Topoquadrangles and Historic Topographic Maps in the past six years. A download is counted when a user select the desired map(s) from the USGS Storeor The National Map Viewer and places that file on their computer or mobile device for further manipulation.