Thematic Maps

In a previous blog we explored the world of topography and how cartographers develop intricate & culturally specific symbols to represent the world on their maps.

This got us thinking about how maps themselves have developed over time – as we moved out of the metaphorical cave and up Maslow’s hierarchy of needs, so has the data we choose to represent through our maps.

Once concerned with just mapping the landforms around us, we now have all forms of thematic maps that show anything from the political, economic or religious features of a given area - rather beautifully described by Barbara Petchenik as “in place, about space”. Whereas a map once showed us the ‘what’, maps now give us insights to help us understand the world we have created around us - our communities & society at large.

One of the best early examples of mapping social data comes from the pioneer physician John Snow who created a dot distribution map to show cholera deaths in nineteenth century London.

Until his map, no one understood the cause of the spread of cholera so they couldn’t stop it. The pattern he discerned from the distribution of deaths on the map lead him to a water pump in Soho. He successfully lobbied to put the pump out of use and new cholera cases stopped – prompting a massive shift in the understanding of public health at the time. Incidentally, as a nod to Snow's actions, the pump now sits as a memorial next to one of the best pubs in London, The John Snow. (somewhat ironic since he was a lifelong teetotaller!)

Thematic maps have developed over time on micro and macro scales. Now you can get a map of almost anything, such as the map below - a traditional data based map showing life expectancy around the world. You can also view the interactive version.

How about something off the wall, such as this from the DogHouse Diaries who used worldwide data to create a map of “what each country leads the world in” – who knew that the USA leads in lawnmower deaths and we had to check our world map to work out that it’s Rwanda with the highest number of women sitting in Parliament.

It is in our modern technological age that these thematic maps can really come into their own. Most thematic maps relate to social issues which change over time. In the past, you would have had to lay transparent maps on top of each other to represent a change – now the digital possibilities are endless.

A fascinating project on the 1760 Jamaican slave revolution is a case in point. You can play with the map at revolt.axismaps.com, according to the project creator, “mapping the revolt and its suppression illustrates something that is difficult to glean from simply reading the textual sources. The colonists and imperial officials who produced the historical record were universally unsympathetic to the rebellion, and we have no documents produced by the rebels. Tracing their locations over time, it is possible to discern some of their strategic aims and to observe the tactical dynamics of slave insurrection”.

Interactive projects such as these take maps created centuries ago and add the “functionality of the twenty-first century” enabling us to understand history like never before.