An interactive map illustrates cities with more than 500,000 individuals rapidly growing in population size from 1800 to 2030.

The image to the right is a photo of an interactive data visual in which urban development is portrayed in cities with over 500,000 inhabitants. The International Institute for Environment and Development illustrate this interactive graphic in an easy to use map and grid. Below the graphic, there is a guide depicting how to use the map; however, I think this visual does not need instructions because it is very self-explanatory. The map has information on the population size in these cities from 1800-2030. A user can easily change the year and find the increase in numbers within the populations; one can also zoom in and out of the well-presented map. In addition, one can hover over a city with a keyboard mouse and find information on that city. I believe this visual is explanatory because it is easy to use and simply illustrates the information which provides graphical knowledge over a large period of years, including the future. I think the only negative issue with this map is the difficulty in finding information on a smaller city. Many circles on the map overlap with other cities and it is complicated to hover over the exact city you want to learn more about; however, IIED creates an easy to use grid construction of the information. This part of the graphic allows users to easily find a city in a grid format. This visualization is a good example of an explanatory graphic because it is easy to use and learn the information presented about the growing cities around the world.