I georeferenced a map of Mexico and its natural resources from David Rumsey’s Map collection. I was able to match up the borders somewhat closely, but I had to mostly rely on features such as shorelines and borders with the United States and Guatemala to accurately match points on both maps. Many cities in the Mexico map were depicted with larger points to show population, thus decreasing the precision of the location of the cities.
I got it close, but never quite perfect, which is a little frustrating since it is harder to make more layers in ArcGIS when the map and base layer aren’t perfectly matching. No matter how many points I put down, or how precise I was with the location of these points, I couldn’t quite get it. You can see the georeferenced map here.
I can find the rectified map in a Web Map Tile Service format, a JSON format for GIS, and a JSON format for metadata, which makes it useful in a number of contexts, both on the web and on desktop mapping software.
Georectified maps are starting points for further investigation into the history of spatial information, and in GIS software you can highlight patterns that arise between old maps and newer layers with different information. My favorite example of this is the New York Times’ investigation into redlining and average temperatures in Raleigh North Carolina, where old maps of redlined districts were compared with layers showing green spaces and average temperatures, showing the connection between formerly redlined neighborhoods and the effects of climate change using both new and historical maps.
Georeferencing is great for historical comparisons, but it has some limitations. It isn’t an adequate method for showing movement over time, for one. Georeferencing wouldn’t be helpful for showing the paths of our 3D museum objects. To put it more broadly, georeferencing is more about analyzing old maps than it is visualizing spatial data that one enters into the system. Other technical limitations in the particular software we used included maps around the poles; the system was not able to reconcile the maps near the poles, which was unfortunate since I had a really cool map of expeditions into Antarctica. Overall, it’s a finicky process and I didn’t have perfect results, but it certainly has potential in the humanities!
