USGS Historical Maps Via Topoview

In the days before Google Earth (and similar) one of my favorite pastimes was to pour over printed maps. And my favorite maps were the large scale topographic maps produced by the the USGS, the United States Geological Survey. Back in the day we actually went to a store and bought the maps we needed and a collection of large-scale maps covering the Adirondacks was a non-trivial investment.

Going back to the mid-90s the USGS has also provided digital access to maps from its' vast library. That access has evolved considerably over the last 20 years culminating in the recently unveiled Internet application called TopoView. TopoView provides public access to (nearly) the entire library of historical topographic maps created by the agency over the past 135 years; over 170,000 map sheets from different editions (year and scale). If you want to dive right in the link goes to the TopoView home page where you'll find a short video that explains how to use the application. Or just go straight to the application and start poking around. The TopoView interface is well designed and well executed. Best of all, it's fun to use; at least I think so.

A screen capture of the TopoView interface. The box in the lower left provides details map sheets available for the selected grid cell. Clicking the map image in the box opens a high resolution image of the map. Links in the box allow maps to be downloaded in several different formats.  

TopoView is a remarkable application and, for the Adirondacks, it provides a unquie source of historical data. The Adirondack region has undergone two great transformations over the last 200 years. The first was the destruction of vast swaths of virgin forest by logging and fire starting around 1850 and lasting into the early 20th century. The second transformation has proceeded more slowly but is well underway. It is the regeneration and succession of the Adirondack forests following the  protections put in place starting in the 1890s. The maps available via TopoView provide a timeline and geographic snapshot of  that second transformation.

Let's look at some maps that illustrate what I'm talking about. The four maps that follow are:

• 1898 - USGS 1:62500-scale Quadrangle for Thirteenth Lake. The map is overlaid with two current hydrologic data sets (also available from the USGS). The red lines represent streams and rivers and the dark blue areas are represent water bodies (lake and ponds).
• 1954 - USGS 1:62500-scale Quadrangle for Thirteenth Lake, NY - with hydro overlays
• 1954 - USGS 1:62500-scale Quadrangle for Thirteenth Lake, NY - water boundary overlay is not shown to make it easier to see the representation on the topographic map
• 1997 - USGS 1:25000-scale Quadrangle for Bakers Mills, NY - a higher resolution recent map

Map 1: 1898 - USGS 1:62500-scale Quadrangle for Thirteenth Lake. The map is overlaid with current hydrological data. The red lines are streams and rivers. The dark blue areas represent water bodies (lake and ponds). The mis-alignment between this 120 year old topographic map and the modern GIS layer is clearly visible. But this map was made in the days before aerial surveys and it met the accuracy standards of the day. Quite remarkable actually, this is not easy country to move around in.

Map 2: 1954 - USGS 1:62500-scale Quadrangle for Thirteenth Lake, NY - with overlays. The modern boundary layer for the Mud Ponds aligns closely with the outlines shown on the topographic map.

Map 3: 1954 - USGS 1:62500-scale Quadrangle for Thirteenth Lake, NY - water boundary overlay not shown. Note the addition of the trail that reaches the ponds.

Map 4: 1997 - USGS 1:25000-scale Quadrangle for Bakers Mills, NY - a higher resolution recent map with water boundary and stream overlays. The current hydrological overlays align closely with the topographic map. 

I download the topographic maps using the TopoView application and loaded them into qGIS (Quantum GIS, open source GIS) so I could add the high resolution water layers that provide an up-to-date geographic context. Map one, from a USGS map printed in 1898, shows an approximation of the size, shape and location of the two ponds (Mud Ponds, in the Siamese Lakes Wilderness). But that's not to say that the map did not meet the accuracy standards of that time. Given the survey methods available then the map was very likely up to standards and accurate enough. If you wanted to visit these ponds that map could serve as your guide. While it is ultimately true for all data, geographic data is always an imperfect and approximate representation of the real world. It's easy to forget that when reading a well produced map from a trusted source. USGS topographic maps are produced to meet an accuracy standard that defines acceptable levels for accuracy and errors. You can learn more about this here.

Map two shows the same water layers overlaid on the USGS map from 1954 and, as you can see, the alignment between the USGS map and the modern water layers is significantly better. This map also shows a trail. That trail was not shown on earlier coverages of the area. Map three is the same configuration but with the display of water boundaries turned off. This makes it easier to see the ponds as they are represented on the topographic map.

Map four was made using the current base map from 1997. The newest map is higher resolution with a scale of 1:24,000. The earlier maps represented a scale of 1:62,500. The alignment of the water layers with the latest topographic map is very good. An interesting side point is that the trail visible in the 1954 map is no longer present on the map. See my post on a recent hike to these ponds to learn more about why this point was important to me.

The maps I downloaded from TopoView to create the above images were retrieved in the GeoTiff format. That format provides the highest quality option for maps retrieved from TopoView. The KML option is nearly as good and works best with Google Earth. The GeoPDF format is best if you want to print a copy of a map that you download. And the JPG option is good for viewing maps directly on your computer, especially in a web browser.

In upcoming posts I'll discuss additional opportunities and issues associated with this incredible source of historical geographic data.