This is especially true if you are trying to create a visualization of how the US presidential election could turn out. The New York Times team that created the Path to the White House graphic did a fabulous job of addressing the vagaries of the electoral college system. 

The biggest issue with conventional color coded maps is that the vast majority of states rarely change allegiance leaving about a dozen or so battlegrounds. There is also the problem of uneven population density so the map appears to be predominantly republican by area, but most of the 24 states that went red have small populations and correspondingly few electoral votes. 

The interactive tree created by the Times let users follow the potential paths and see what the results would be. I can see others doing something similar in 2016.