One issue with choropleth maps is that geographic areas that are small in area can oftentimes become indecipherable when viewed on a small scale map. Take for example, a map of the United States. The states located in the New England region are far smaller in size than states along the Western coast. A choropleth map of the entire contiguous United States would show the New England states at such a small size that it would be illegible to the naked eye without producing an inset map showing the area enlarged.
There are solutions to this dilemma, especially when the actual geographic size is not important but maintaining a loose spatial organization is. One solution is the creation of a Tile Grid Map. Tile Grid Maps assigns one equally sized shape such as a squire or a hexagon for each region, regardless of actual geographic size. This cartographic technique not only resolves the issue of legibility for shading smaller geographic areas but it removes the artificial visible weighting that larger geographic areas lend to a choropleth map.
For more about this cartographic approach, read Danny DeBelius’ write up on NPR’s Visual Teams’ blog: Let’s Tesselate: Hexagons For Tile Grid Maps. He points out examples of this style of map are gaining popularity on such news and analysis sites as FiveThirtyEight, Bloomberg Business, The Guardian, The Washington Post, and The New York Times.