Proportional circle map

 

http://personal.frostburg.edu/crkitzmiller0/maps.htm

This is a proportional circle map that shows the number of births in the U.S. by state.  In these maps they use size of the circle to indicate quantity.  A bigger circle means there is more of whatever is being measured and a smaller circle means there is less. In this map its easy to see that the most births occurred in California. These maps are great at showing comparisons because the information is easy to interpret.