View Full Version : Historical Maps Available Soon from USGS
08-16-2011, 09:19 PM
USGS is currently scanning and georeferencing historical USGS quadrangles and will make them available "soon" for download or purchase. More info in the Fact Sheet: http://pubs.usgs.gov/fs/2011/3009/fs20113009_013111.pdf
Could you please explain exactly what the difference is between a "historical" quad map and say a standard, everyday, currently available 7 1/2 min quad map? Thanks
08-18-2011, 11:19 PM
I'll try my best, Lee.
The Fact Sheet begins with "The USGS Historical Quadrangle Scanning Project (HQSP) is scanning all scales and all editions of approximately 250,000 topographic maps published by the U.S. Geological Survey (USGS) since the inception of the topographic mapping program in 1884."
Two ways in which what they call "historical topograhic maps" differ from the standard, everyday, currently available 7.5 min quad maps are:
When Created - The 7.5 minute quadrangle series, at least those in the Smokies/Tennessee Valley area, were not created until the 1940s and later. These maps have already been scanned and georeferenced in recent years. The maps they are now scanning were created and printed as far back as 1884.
Scales & Coordinates - All the 7.5 minute quadrangle series maps were created at a standard 1:24,000 scale. The "historical" maps they are now scanning were created at a variety of scales. For example that of the map below is 1:125,000. It was created/published in 1926. Although not visable, I imagine even this early map incorporated the North American Datum of 1927 (NAD 27), which is common with the more modern day maps and forms the basis for the georeferencing step. Most, if not all, of the "historical" maps will be absent the Universal Transverse Mercator (UTM) coordinate system which was not developed until the 1940s.
08-19-2011, 10:18 AM
Aren't these already available for download?
08-19-2011, 01:18 PM
Good question, NDuncan. Yes, but as JPEGs and, I think, as "standard" PDFs. The new downloads will be essentially scans of the old topo maps with the added feature of being georegistered. This is already the case with the 7.5 minute series topographic quadrangle maps. Among the format options available to end users: GeoPDF data files.
So, okay... what are GeoPDF data files? Quoting from http://store.usgs.gov/locator/about_digital_maps.html
"The GeoPDF format is an extension to Adobe's PDF 1.3 and higher versions enabling GIS functionality within standard PDF files. This format is designed for the efficient distribution and communication of rich spatial data to anyone who needs to view, review, verify, update, or print it....
GeoPDF files are not a replacement for native GIS formats. GIS professionals still need the original files for editing or updating spatial data. GeoPDF files enable non-GIS professionals, field technicians, business executives, and their colleagues to utilize rich spatial information. Users can view and print GeoPDF files with the free and ubiquitous Adobe Reade, and they can do more with the data using a free plug-in called TerraGo Toolbar. Users do not have to install this plug-in to view GeoPDF files."
With the TerraGo Toolbar™ you can "do things like measure distances between objects in the map, add your own comments to specific places on the map, view the files in conjunction with Google Maps, or even integrate them with your GPS to track your position on the map." More info at http://www.terragotech.com/products/terrago-toolbar/register.
Admitttedly this thread was somewhat off topic to begin with with the potential to become even more so, but the prospects of using a mobile version of an old Park map GeoPDF to navigate to the spot of old stream-side (naturally ;) ) ruins not shown on the later quads is very intriguing to this admitted mapaholic. Now, I just need to come up with the dough to purchase a capable handheld GPS. :smile:
08-19-2011, 01:42 PM
No it is a good thread. Thanks for the explanation, I didn't understand what the difference was here as opposed to what is already available. Looking at alot of those maps' contours makes me think that the map makers did a whole lot of estimation of the terrain rather than actual surveying, but they are all really cool
Thanks i just spent about an hour downloading and installing the viewer for these maps from 1926 up to the 70's.
Found it interesting to see how the trails, railroads and access points changed over time. :rolleyes:
Thanks again. :biggrin:
Thanks for taking the time to explain this. I'm not sure i understood every detail as you stated but i did get the gist of it and can see where this might be going. I dearly love park history and maps like this could be invaluable for exploring past places. Thanks again and i will be following updates.
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