Flow Maps

Flow maps are used to show the movement of something from one place to another. This can be anything like water, goods, people, etc.


http://www.mundi.net/maps/maps_014/
This map shows telephone traffic between the depicted countries. The thickness of each line is proportional to the yearly volume of traffic.
This is a map because it shows the relationship between the countries, and specifically the network of communication between the countries shown.