What is GIS?

To put it into a simple definition, GIS or geographical information system is a way for historians to try and tackle issues with space. Peter K. Bol writes that GIS presents “a platform for organizing data with temporal and spatial attributes—population, tax quotas, military garrisons, religious networks, regional economic systems, family history, and so on—representing them graphically and analyzing their relationships.” GIS also gives historians a better look at/understanding of maps while allowing them to go beyond simply mapping. To be even more specific, HISTORICAL GIS refers to the ways in which researchers take advantage of geospatial technologies for research and teaching by combining geohistoire (an idea of historian Fernand Braudel which maps human activity where possible), historical geography and spatial as well as digital history.

Kelly Anne Knowles refers to GIS as both a “superb tool” as well as something which is “problematic” for history. GIS is superb because “it allows one to visualize the geographic patterns embedded in historical evidence, examine evidence at different scales, aggregate date from smaller to larger units, and integrate material from textual, tabular, cartographic, and visual sources provided that they share common geographic location” and problematic simply because it relies on mathematics. Mathematics is an issue for most historians who tend to focus on images rather than quantitative data.

Let’s take a look at some of the case studies included in the reading. The first I am going to bring up is “The Salem Witch Trials Archive” which use primary sources such as court documents and proceedings which took place in the colony. The archive becomes a great resource for a variety of historians studying early America. In addition to just being an online archive the project has taken on an aspect of GIS by linking biographical information about those involved in the Salem witch trials (those specifically mentioned in the documents) to the locations of their homes. Of course, it is obvious that it shows the researcher where each individual lived; but for what purpose? The creator of the Salem Witch Trials archive, Benjamin C. Ray uses GIS in his project to illustrate that “witchcraft accusations did not reflect clear geographical and social divides between Salem’s merchant class and less wealthy farm families, as the prevailing view has long contended.” As you can see, this is an example of how GIS can answer questions that have long been invisible to researchers.

I spent a lot of time also looking at chapter 10: “What Could Lee See at Gettysburg” because I am passionate about Civil War history and I wanted to see how GIS is making an impact in that realm. The historical question being asked is, of course, in the title. However the bigger question would be: “why is it so important to know what exactly Lee saw at Gettysburg?” Historians want to know why General Lee gave the “go ahead” to what would eventually be known to historians as “Pickett’s Charge” in which Confederates were simply massacred. To me, the obvious response would be to look at what Lee had to say about the event, or a soldier from either side who was present. Perhaps that way we could get a good idea of what transpired to cause this disaster for General Lee. Of course, we can try and see what Lee saw by visiting the battlefield itself. The National Park Service has been working hard to maintain the battlefield for historians and tourists alike. So why GIS? Why do we need it when it is possible we could find out from an eye witness or even go to the preserved battlefield ourselves? There are several other questions asked within the chapter itself. “Can the evidence of sight be used to test the credibility of generals’ post hoc justifications, such as Longstreet’s explanation of his long counter march on July 2? Did the Union’s possession of Cemetery Ridge give Major General George G Meade and his intelligence officers’ superior knowledge of the battlefield and enemy movements in addition to providing them more defensible positions?”  Knowles makes the argument that both Lee and (union) General Meade would have been excellent resources due to their expertise in topographical mapping which they both gained at West Point.

GIS is able to assist us in this endeavor by doing what the generals in 1863 could not. “GIS uses a digital model of the terrain to determine points and areas that are, or are not, theoretically visible from a known viewpoint.” Curtis Musselman, cartographer and GIS coordinator at Gettysburg National Military Park has created renderings of historic roads and lanes, fence lines, property boundaries, and buildings as they stood in 1863. “He also provided a digital elevation model (DEM) developed for Adams County by a private firm in 1996 and a set of contour lines at five foot intervals that had been interpolated from the DEM. The elevation data meets the US Geological Survey’s national map accuracy standards for 1:4,800 scale mapping.” The digital terrain that has been created using GIS is a simplified version of the reality. What makes it stand out to researchers is that it provides us with information that even the great generals did not have: the big picture.

What researchers ended up discovering was that General Lee had an excellent view from the Lutheran Seminary on July 2, 1863. There is a monument to Lee at the park where it is believed he was supposed to have watched the final assault. “Standing with his field staff on the edge of a copse of woods near the center of the Confederate’s line of attack, he would have had a fairly clear view across the undulating fields to his objective…the GIS viewsheds help one imagine what might have gone through the minds of soldiers and commanders that fateful day.”

Another component of GIS is offering students to make new discoveries about history using technology.  For students who are living in a world where they look up everything on the Internet, the realm of digital history and GIS is a perfect fit. Students can apply their skills with technology to mapping, organizing files, building databases and most importantly, complementing their writing with a visual representation. In addition to this, using GIS will allow students to find spatial data and have their own visual representation of history without having to imagine what it would look like or what effects geography made on the resulting history. GIS also helps students frame research questions and engage in analytical thinking. For example, students might be compelled to ask themselves: “What is spatial about this research?” “Why does space matter?”
How did rivers affect the eventual manufacturing?” etc.

Like many other components of digital history, it appears we still have a lot to learn about geospatial mapping; however, it is exciting to see how technology is playing a role in helping us understand the past and even take a look at images that were once long gone.