

I search on Pinterest to see the visualization relate to population density. Which is another way to visualize amount of population. I found that the population density visualization more attempt to use clusters to shows the feeling of density. And also the real life reference of traffic on the highway in the night give me inspiration.

How has the age distribution of the U.S. population evolved from 1990 to 2000?
The circle cluster shows clear density of population size for each group, supporting comparison.
