ABOVE IS AN ORDINARY MAP OF THE WORLD. Roughly speaking, on a map like this, the sizes of the countries of the world are in proportion to their actual sizes on the surface of the planet and their shapes are the same as their actual shapes. (This is only approximate though, since some distortion is inevitable when you go from a spherical planet to a flat map.)

It's possible, however, and sometimes very useful, to redraw the map with the sizes of countries made bigger or smaller in order to represent someting of interest. Such maps are called cartograms and can be an effective and natural way of portraying geographic or social data.

BELOW FOR EXAMPLE IS A CARTOGRAM THAT SHOWS THE HUMAN POPULATION OF THE COUNTRIES OF THE WORLD:

In this map the sizes of countries are proportional not to their actual landmass but instead to the number of people living there; a country with 20 million people, for instance, appears twice as large as a country with only 10 million.

Although the figures for populations of countries are well established and familiar to many, the cartogram provides a new way of looking at them and in particular makes clear the enormous disparity in the population of different regions. Note how large India and China have become: between them these two countries account for more than a third of the population of the world. On the other hand notice the near disappearance of Canada and Russia, the world's two largest countries by land area, which have relatively few people in them.

Notice also how the lines of latitude and longitude have become distorted by the growing and shrinking countries. This is an unavoidable consequence of the cartogram transformation: in order to give the countries the right sizes and still have them fit together you need to warp things a bit. The method used here, however, does a pretty good job of keeping the map recognizable.

Cartograms are most often used to show population data, but there is no reason why they need be limited to population. They can in principle be used to show almost any quantity. BELOW is a cartogram of the world in which the sizes of countries are proportional to GROSS DOMESTIC PRODUCT, which is a measure of how much wealth a country's economy generates, and hence, to an extent, of the wealth of the country's inhabitants:

Notice how America and Europe dominate this map, along with Japan (yes--that huge dark-green island on the right really is Japan), while Africa dwindles almost to invisibility.

Now here are a few more cartograms. In all of the maps on this page the countries have the same colors, which helps to identify countries in the cases where shapes have changed a lot.

THE CARTOGRAM BELOW SHOWS CHILD MORTALITY:

THE CARTOGRAM BELOW SHOW PEOPLE LIVING WITH HIV/AIDS:

THE CARTOGRAM BELOW SHOWS TOTAL SPENDING ON HEALTHCARE:

THE CARTOGRAM BELOW SHOWS ENERGY CONSUMPTION (INCLUDING OIL):

(Not surprisingly, this is the exact same cartogram for GREENHOUSE GAS EMISSIONS).

All text and images used by permission.