Illustrating the Arc of European Colonialism Using a Dot Plot

A while back I was thinking about European colonialism and the enormous impact it’s had on world history. Wouldn’t it be nice to have a simple visualization to illustrate colonization and decolonization around the world? It occurred to me that a dumbbell dot plot would work well for this task. Here’s what I came up with:


The chart shows the dates of colonization and independence of 100 current nations. The countries are organized into broad regions (Asia, Africa, and the Americas), and sorted by date of independence. Color represents the principal colonial power, generally the occupier for the greatest amount of time.

There are many interesting patterns visible in the chart. For example, you can clearly see Spain’s rapid conquest of Central and South America, and then even more rapid loss of its colonies in the 1820s. The scramble for Africa in the late 19th century stands out well, as does the rapid decolonization phase of the late 1950s through early 1970s.

About the Data

To reduce complexity to a manageable level, I set some limitations on what countries to include. First, the chart shows only those countries victim to Western European colonialism. I don’t include Ottoman, Japanese, Russian, American, or other colonial empires. I also don’t include territories that are still governed by former colonial powers (e.g. Gibraltar). This gets controversial and complicated. Countries that were uninhabited upon discovery by colonial powers are also not included. The same with countries that later gained independence from a post-colonial state (e.g. South Sudan).

The dates of independence come from the CIA World Factbook (here). Dates of colonization were derived by my own research, mostly from Wikipedia country pages. I quickly found that establishing a date of colonization is a somewhat subjective decision. Do you choose the date of first European contact? Formal incorporation of the territory into the colonial empire? For the most part, I chose the date of the first permanent European settlement. Notes on the rationale for the date chosen are include in the data spreadsheet (below). In looking at the chart, it’s important to remember that in many cases colonial subjugation was a long process, moving from initial contact, to trade, conquest, settlement, and incorporation.

Constructing the Plot

I wanted to make this plot using ggplot2 in R, but was not sure about best approach. So I reached out on Twitter to dataviz guru and dot plot enthusiast @evergreendata

The response from the #rstats and dataviz community was extremely constructive and useful. Users  @hrbrmstr@jalapic@ramnath_vaidya, and @plotlygraphs all provided great examples (here, here, here, and here, respectively). In the end, I chose to adapt the approach taken by @jalapic.

A quick note on color: I choose colors from the flags of the principal colonial powers to represent them on the plot (except for the Netherlands for which I picked orange). The idea is to make it easier for the viewer to match the color with the country without having to always go back to the legend. I’d be interested in any reactions to this approach. In general, I’d be thrilled with any feedback on how to make this plot better.

Data and code for the plot:

8 thoughts on “Illustrating the Arc of European Colonialism Using a Dot Plot

  1. Hi Ken,

    I liked the post. In fact, I liked it so much, that I thought I’d take a crack at reproducing your graphic in Tableau. It took me a couple of hours to complete because I had to do a lot of detailed things like data reshaping, picking and setting custom colors, and studying your design elements. I produced two charts – one sorted like you did by when the countries gained their independence. I also did one sorted on when they colonized. I thought that was an interesting way to look at the data. If you are interested in seeing these renditions, just let me know. Thanks for sharing!


  2. Hi Ken,
    I like this post and I like that it is easy to read. My first thought was wouldn’t it be interesting to see this data along side the economic development of each of the countries on the chart? When did the economic development of Uganda peak, for example. During its colonial period or after? Why might that be? etc. I am in no way suggesting that you do this. I know that I don’t have that kind of time and I don’t know who would want to punish themselves in that way, but it would be interesting to see and it might open other roads of inquiry.

    • Hi Paul,
      I’m glad you like the post!
      You’re right, it would be very interesting to incorporate economic and other variables into the plot. Have you ever seen the Gapminder World website? It has tons of economic, demographic, and health indicators and allows you to make animations of how these change in a country over time. In the case of Uganda, you can see that GDP per capita initially grew after independence, then dropped from about 1975 – 1990, and then began to grow again. See

  3. Ken, I love the new lens your plot creates. It makes it easy to pick out surprises (to me), like the 2 countries outside of the Americas that Spain colonized (Equatorial Guinea???), and how much older some of the colonies were than others close by (The UK in Jamaica, for instance.) Also Portugal’s early and long hold on its colonies really stands out. Oh yeah, and who knew that Portugal colonized Oman?

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