Choropleth maps

Choropleth maps show statistical data aggregated over predefined regions, such as counties or states, by coloring or shading these regions. You can draw states according to their population, gross domestic product, car owners, and the number of national parks. You are not limited to a single variable; indeed, you can merge different values from more than one attribute associated with spatial objects.

The following figure shows a map of European countries colored according to gross domestic product values. Legend on the right shows the five classification intervals. Values were normalized to Eu-27 average (EU stands for the European Union, in the period 2007-2013 when it had 27 countries):