Justin Madron’s map of demographic change in the early American South grapples with the movements of enslaved, free, and Indigenous people after America’s founding. For this Behind the Map, Madron, associate director of data visualization at the Center for Geospatial Solutions, details how he and his colleagues iterated through approaches to bring this history to life in an impactful and intuitive way.
Maps.com: What was your inspiration for this map? What spurred you to create this? Who is it intended for, and what do you hope they take away from your map?
The inspiration for these maps came from Ed Ayers, a renowned historian of the American South. He envisioned an atlas that visualized and traced the movements of people who left few marks on the historical record over a span of 220 years. The maps were designed to add a visual dimension to the rich individual and group narratives detailed in the atlas.
This work is intended for a broad audience: historians, educators, students, and anyone curious about the historical dynamics of the American South. My hope is that people come away with a deeper appreciation for the intricate and complex tapestry of US history. These maps offer a compelling way to explore long-term patterns and understand the forces behind these movements. For mapmakers, I hope they serve as an example of how cartography can reveal changes over extensive time periods and inspire creative approaches to representing historical data.
Maps.com: Can you talk a little about how you built this map? What tools and processes did you use?
The maps were created using ArcGIS Pro for spatial analysis and mapping, followed by refinement in Adobe Illustrator for polishing and standardization. My colleague, Nathaniel Ayers, a talented graphic designer, played a crucial role in ensuring the visual consistency of the final products.
The process involved significant spatial data manipulation to align historical census data with county boundaries that changed over time. After the maps were finalized, we incorporated them into ArcGIS StoryMaps alongside text, supporting maps, and interactive elements to provide additional context and accessibility for users.
Maps.com: Did you encounter anything unexpected or surprising while you were creating this map? Is there anything you’d like to highlight or call out?
Yes, we faced several unexpected challenges, especially when deciding on the best methodology and style. Initially, we experimented with kriging to create “movement contours” for each decade, aiming to show migration trends. While visually interesting, the method didn’t convey the level of detail we needed.
We ultimately settled on a hexbin methodology, which offered a more comprehensive representation of population increases and decreases. The hexbin approach provided clarity and allowed us to identify nuanced patterns in migration over 220 years. One surprising takeaway was how dynamic and varied the population shifts were, revealing significant regional differences in movement patterns that shaped the South.
Maps.com: If you could revisit this map, are there any changes or updates you would make? Why?
While I’m satisfied with the maps themselves, I would approach the process differently. Given the iterative nature of the work, much of it was manual and time-intensive. If I had to do it again, I would script the workflow programmatically.
Developing a model to automate the aggregation, analysis, and symbology adjustments would not only save time but also allow for easier replication and updates with new data. This would improve efficiency, ensure consistency, and reduce review time while enabling broader scalability for similar projects.
Maps.com: What made you want to start creating maps in the first place?
The need to visualize the movement patterns of the South over 220 years for a printed atlas was my starting point. Cartography has always fascinated me as a way to distill complex information into a visual format that is both accessible and impactful.
Maps.com: What’s your favorite map?
My favorite collection of maps is from Charles Paullin’s Atlas of the Historical Geography of the United States. Published in 1932, it contains nearly 700 meticulously detailed maps across 166 plates, addressing a vast array of topics.
I had the privilege of working on a project with the Digital Scholarship Lab to digitize and enhance these maps, turning the static atlas into an interactive application. This project remains one of my favorites because it brought historical maps to life, making them accessible and engaging for modern audiences.
Maps.com: What kind of mapping projects would you like to explore next?
I’m interested in pushing the boundaries of cartography through experimental techniques like hand-drawn maps. With a background in landscape architecture, I’ve always loved hand drafting, and I see value in blending traditional craftsmanship with modern tools. There’s something uniquely personal and artistic about hand-drawn maps that I’d love to explore further.
Featured Contributors
Justin Madron
Justin Madron serves as associate director of data visualization at the Center for Geospatial Solutions (CGS), bringing extensive expertise in geospatial data management systems and digital storytelling. Before joining CGS, Justin held the position of associate director at the University of Richmond’s Digital Scholarship Lab, where he played a key role in leading award-winning digital humanities projects and data visualizations. One notable project, “Mapping Inequality,” garnered recognition in publications such as National Geographic and the New York Times.
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