Continuously Variable Proportional Circle Map

http://www.nytimes.com/interactive/2011/11/14/us/Changing-Face-of-the-Rural-Plains.html

These maps utilize circles to create data point. The clear circles depict population decrease, while the brown depict a population increase. The size of the circle illustrates the number of people, as is shown by the scale. This map relates the scale to the population of the hispanic and white race in 7 states.