Territorial Evolution of the United States #IronViz

This is my second year (and the third time) participating in the #IronViz. The first time I participated was during the second feeder round last year where I submitted an entry looking at Women Heads of Government. The second time was the Mobile Viz round where I looked at lives lost on Mt. Everest. This time Tableau requires the participants to use the new Geospatial feature released with Tableau 10.2.

I personally like these feature based challenges as much as I like the topic based ones. This is because it allows me to do something in Tableau that I don’t necessarily get to do at work. When they announced the Mobile Viz round last year, I had played with it a little bit beforehand. You can read about my first attempt on the Tableau Public blog. However, it was only after this and my IronViz entry, that I got to use it at work. The experience helped me bring this change faster to my workplace. This time around I don’t see a chance of me getting to use the spatial data feature at work at all since we don’t have any data in this format. And so, the IronVIz (and any other personal projects I might do later) is the only chance of me using it and learning something new. However, the most difficult part about  IronViz in my opinion is finding the right data.

Finding Data

Since the data had to be in the spatial format, finding a data that tells a story became all the more difficult. Some ideas I had and scratched can be seen from the image of my downloads folder below:


I started with NYC Open Data and found interesting data sets about Subways stations, Parks and Gardens, but I wasn’t happy with the result.


I looked at Phoenix bus stops, Meteor Impact sites but still couldn’t find anything I liked.


I then landed onto this nice file showing the Roman Empire on ArcGIS that someone had made. I was really fascinated to use this and show the expansion of the Roman Empire with time. The problem- the data was only as of 14AD. I couldn’t find something that showed how the map changed with time.


I loved this idea so much I started looking for similar data for different empires, civilizations and countries. That’s when I came across this link on gizmodo. It basically shows ‘The formation of the United States of America in one animated map’.


I started searching for shape files that showed how the United States was formed. I hit jackpot with this amazing work done by researchers at Newberry Publications. A brief description of the terrific project is below.

A project of the William M. Scholl Center for American History and Culture at The Newberry Library in Chicago, the Atlas of Historical County Boundaries is a powerful historical research and reference tool in electronic form. The Atlas presents in maps and text complete data about the creation and all subsequent changes (dated to the day) in the size, shape, and location of every county in the fifty United States and the District of Columbia. It also includes non-county areas, unsuccessful authorizations for new counties, changes in county names and organization, and the temporary attachments of non-county areas and unorganized counties to fully functioning counties. The principal sources for these data are the most authoritative available: the session laws of the colonies, territories, and states that created and changed the counties.


The Viz

I started working on my viz using this data. I had some trouble putting it in the right format. I spent sometime using ArcGIS to see if it’d be easier to get the data in the desired format through that. But eventually I was able to make it work just using Tableau (and a little bit of Alteryx). A special thanks to Kent Marten for his readiness to help on twitter and to Adam Crahen for his blog showing the method to use QGIS.

My first iteration was all black and the shapes stood out but I wasn’t sure if I liked it. I showed it to a few people and got mixed reviews.

I spent a few hours working on this everyday and was happy how this was turning out. Then on one find Thursday I login to twitter and find this:

An IronViz entry by @VizPainter aka Zen Master Joshua Milligan. If you have seen his viz. you already know why I am mentioning this. I was building the viz using the same (or almost the same) data. The Newberry website has two different types of data- one broken down by counties and another by states. While I had downloaded both and had tried working on the data with counties, I did not use it. This is mainly because I wanted the user to go through the entire viz and see how the map of United States came to be. Having the user go through the 17000+ changes to borders seemed a bit like a terrible punishment. But here’s my attempt if you are interested.


However, what Joshua was able to do with the same data set was amazing. He connected it with related events in history and showed them brilliantly on a timeline. After I discovered Joshua’s entry, I spent the next few hours pacing, worrying, thinking, deep breathing, and pacing a little more. I wasn’t sure what I was going to do. So I decided to reach out to him on Twitter to tell him that I was using the same data as he did. I told him about all the ways it was similar to his entry and all the ways it was not. What happened next was amazing. Not only was he encouraging about me submitting my viz., he suggested me some much needed changes to make it better.

Over the next few days I continued to work on the viz. I have mainly broken down the viz. in 3 parts where the first two work together. As you slide through time using the date parameter, the top most tile shows the progress. You can hover over the map to see details about each addition.

Territorial Evolution of the United States.png

I also decided to show Alaska and Hawaii separately in a corner (as most maps do) to make the best use of space and so that continental US doesn’t shrink in size.


While you change the dates, the second tile shows you the change(s) that happened on that particular date. I decided to show this separately for two reasons. One, so that the user can focus on the change alone if they want to. And second, because sometimes the change happened in a tiny part of the map that it may not be easily noticeable.

The third and final tile let’s the user explore a state of their own choice and see how it got it’s shape. I decided to group some states together as it made the most sense. On several occasions a large piece of land broke down into several states or territories and it got difficult to group it with any single state. So I decided to leave them as is and let the user explore on their own.

Finally, I also made a phone compatible version so the user can enjoy the viz. regardless of the device they’re reading this on.

Mobile-Territorial Evolution of the United States


I’ll end this with a fun fact. Even today, border changes continue to happen. As recently as January 1, 2017, the border between North Carolina and South Carolina was clarified following years of surveys and negotiation, moving 19 homes across state lines. 

I hope you enjoy the viz. and find it interesting to learn how United States got it shape. Check it out here.

Suraj Shah