For this blog, I chose to use AllMaps to georectify a historical map of a small neighborhood development in North Mankato, right next to Spring Lake. The original map comes from the Minnesota Digital Library. It is titled Map of Hodapp’s Addition to North Mankato, Minnesota and was published in 1900.
By using AllMaps, I was able to overlay a section of the historical map onto a modern map by creating reference points around certain features that I could recognize, such as street corners.
Here is the link to my rectified map: Allmaps Viewer
I would say this process did change how I think about spatial DH projects, even though my only prior knowledge is what has been covered in this class. When I have thought about spatial concepts in DH thus far, it has usually been on a larger scale. Working with a small neighborhood map showed that spatial DH can be useful for studying even very specific places.
On the map page, there are a few options for different formats for the rectified map to be exported and accessed in. The version I linked above is one of these views, which is an interactive web map. There is also a georeference annotation link, which leads to the alignment information that was used to place the map. In addition, the map can be accessed as “XYZ map tiles” which would allow the map to be used in other mapping platforms or GIS tools.
There are several possibilities that come up when a map gets georectified. Some examples I had in mind were things like layering the map with census data or possibly later maps to study how the area around Spring Lake has changed.
In addition to all the possibilities that come with it, there are definitely some problems to be considered. For one, the original map may not be perfectly accurate, and things like bodies of water or street names or locations may have changed. This is true for the map I georectified. While the streets are all in the same place, the names of several of them have been changed. Because of limitations like this, the georectified maps should still just be treated as approximations.
One area of research where this would not be appropriate would be for research requiring precise measurements. It would also not work well for maps that are symbolic or not meant to represent exact data or places.
Doing this with a hand drawn map is awesome Ronan! Its so interesting that even though something from back then was not precisely calculated and hand drawn, it can still be lined up to current maps today! I really appreciate your comment on the scale of DH here, I completely agree that a lot of the time we look at DH in the big picture, focusing on global impact, while a lot of the time, the most direct impact are in small localized projects!
I really like how you focused on that specific neighborhood in North Mankato. It effectively shows how these tools work for local histories, not just big geographic trends. Your idea about layering census data is super smart, this can really help connect the physical map to the actual people who lived there. Also, good call on the difference between precise measuring and historical approximation; that’s definitely a key distinction we need to keep in mind for future projects.