Dot Distribution Map

http://depts.washington.edu/chinaciv/geo/people.htm

A dot density map is a map type that uses dots to show the presence of a feature or a phenomenon. They rely on visual scatter to show spatial patterns. In dot distribution maps, the size of the dots is scaled in proportion to the intensity of the variable. The map above shows the distribution and density of China's population. One tiny dot indicates 50,000 people.