This morning (in Sweden) I woke up early to watch the 2012 presidential election in United States. I watched different news sources but all of them presented a geographical map of the results instead of cartogram results, giving the impression that Republican candidate had won the election by a landslide since more than half of the United States of America was painted red (image below taken from the 2008 election, as an example):
As it turns out that is not the case. States that are smaller by area, but larger by population (and therefore electoral votes) have a greater impact of the result than what is visible on a geographical map.
There are alternatives, such as a demographic map or cartogram which display the area equal to importance. This gives a more correct visualization of the actual result than a geographic map:
Still, what’s displayed on the news worldwide today is the geographic map. It may be that what we are seeing is an established convention, but the visualization fails and you need to explain to your consumers how to read the map. I think it would be more obvious to the consumer if a cartogram map were used.
So why are election results presented on a geographic map instead of a cartogram map?
Images from the article Transforming the Electoral Map: Beyond Red and Blue