Geo-referencing Guidelines

The nature of geo-referencing

We’ve already done a transcription exercise, which helped us experience and think about different kinds of texts and archival creation. It was awesome.

In this assignment, you will be geo-referencing some maps from the David Rumsey Map Collection. But what is geo-referencing exactly?

Think of a nineteenth-century U.S. map. It’s probably distorted (= wrong) in lots of ways compared to a Google map we can pull up instantly. This could be from a limitation in cartographic technology, skill, or a deliberate distortion to suit the purposes of the original map.

But there can be great value in overlaying historic maps on top of each other or on top of modern maps to visualize spatial change over time. The process of aligning old maps with modern (usually web-based) maps is called geo-referencing (or geo-rectifying or other similar terms). What follows is a conceptual description of what we want to do.

Pretend you have a reasonably accurate (nothing cartoonish or highly stylized) historic map of the U.S. printed on transparent silly putty sitting atop a modern paper map of the U.S. Pretend they are the same scale and size—but even then they won’t line up exactly. Depending on original, the maps may be kind of close, or they might be horribly divergent.

Now imagine stretching your transparent silly putty (the old map) in various directions (push and pulling it at various points, not always symmetrically) to align it with the modern map. To make our alignment stick, push pins through the silly putty at obvious geographic features (river junctions, coastlines) or political features (state borders), or infrastructure (railroads, highways, etc) and make sure they line up with the same features on the modern map.

Now, the putty will be stretched in various directions (often different amounts in different places on the map/image) but will end up being much more closely aligned to the modern one. The two maps will line up very closely in places near to our pins and perhaps less so everywhere else. TA-DA! You have geo-referenced the historic map to the modern one.

Like the transcription exercise, this work helps others use historic maps in digital research. It also helps us think about the difference between modern digital web maps and older analog ones.

Basic Requirements

  • Needs to be a separate PAGE on your portfolio, NOT a blog post
  • ~800 words, but there is no maximum, so take the space you need to describe and analyze your experience.
  • Show me that you’ve done the geo-referencing assignment—to geo-rectify AT LEAST TWO maps via the David Rumsey Map Georeferencer—ideally one of a place you know fairly well, and one you don’t know at all.
  • NOTE: If you spend a lot of time on a map (placing lots of points) and the maps still don’t seem to be aligning very well, move on! Some historical maps can take a zillion points to really get right and that’s not the point of the exercise.
  • Document your experience to a general audience, namely what kinds of features you used, how easy it was to find corresponding features evenly across the map.
  • Must include screenshots of what you’re doing. Before and after shots of the maps would be appropriate, as well as zoomed in images that highlight map details (features) you mention in your description.
  • Clear, concise, and meaningful writing (no fluff!)
  • If you want to geo-reference a map from somewhere else (not the Rumsey Collection), that’s fine! You can use a great open source tool called Map Warper and document your experience with that tool.

Goals beyond the course

Part of the goal of your digital portfolios is to show off your fluency moving between digital/analog texts + tools and qualitative/quantitative methods + analyses. Imagine that you are writing this for a potential employer who is intrigued by the “Digital History” course on your transcript. Describe (in terms of the map exercise) how the relevant aspects of the course help you think differently.

What to comment on

For the project critique, below are some possible themes and questions you might ask yourself and comment on in your response. This is not an exhaustive or restrictive list! But remember, these more pedestrian questions are not as important as the critical reflection component, so don’t spend a lot of words on them.

Map Collections website

  • Was it fun or boring to search or browse for a map?
  • Were you made to feel like you were contributing to an interesting public service?
  • Judging from the Rumsey site, did you get a sense of how the map scans could be used differently after your work?


  • Were you easily able to figure out what to do to geo-reference a map?
  • How “seamless” was the interface–that is, it always seemed to make it easy to go from one step to the next?
  • Did the interface make the experience more or less enjoyable?

Geo-referencing Experience

  • What was your experience with trying to align the maps? What did you learn? Did you get better at it along the way?
  • What kinds of features made it easier to align the maps and which didn’t? How might this make you rethink how we read digital maps?

Critical Reflection

  • This is the most important aspect of your essay!
  • We’ve discussed the difference between digital and analog sources. How did the geo-referencing project confirm or complicate the notion of a map (this question isn’t as stupid as it sounds)?
  • How do analog and digital maps fit into digital history? Namely, how can they increase the utility of digital history research? What are the dangers?
  • How can we use our previous abstract/theoretical readings to evaluate the pros and cons of digital spatial history?
  • Reflect critically on what you’re doing using course readings. The point of the readings is that you can use them!
  • Comment on how the assignment brings up critical issues at the intersection of technology and the humanities.


  • 0-2: Technically the assignment is done, but is entirely descriptive without any critical reflection on your experience, and with rushed writing (unorganized, repetitive) that was hard to follow.
  • 3-5: Displays some critical engagement with the assignment, writing is fine and gives a serviceable picture of what you did. Generally underwhelming.
  • 6-8: Shows potential, but falls short in scope or execution. Usually this score represents a generally good essay that is missing a critical component or is sloppily done. For instance, you might clearly describe your map warping without any broader critical reflection on digital maps generally.
  • 9-10: Carefully written; pulls in different readings from the course to analyze your experience (across all relevant readings from the syllabus); shows significant critical engagement with the assignment in that all description is used to make a broader point.