Cartograms are used for thematic mapping. They are a particular class of map type where some aspect of the geometry of the map is modified to accommodate the problem caused by perceptually different geographies. Standard thematic maps, such as the choropleth, have inherent biases simply due to the fact that areas will likely be very different in size from one another. The tendency to see larger areas as more important, regardless of the variable being mapped, can cause confusion. Cartograms tackle this by modifying the geography, effectively normalizing it to create a map where each area takes on a new shape and/or size based on the variable being mapped. Cartograms therefore depict geographical space diagrammatically as they lose their relationship with true coordinate system geometry. There are four main types of cartogram which each represent the mapped variable differently – non-contiguous, contiguous, graphical and gridded.  

The intersections between art and cartography go far beyond the notions of design and illustration, since mapmaking invariably has multiple cultural, social, and political dimensions. Considering this broader perspective, this entry provides a review of these different contemporary intersections, by exploring three main types of relationships: 1) cartography influenced by artistic practices; 2) map art or maps embedded in artistic practices; and 3) cartography at the interface between art and places. These will be discussed in detail following a brief overview of the main historical markers from which these types of relationships between art and cartography have emerged.