Module 10 - Cartography - Flow Line Mapping

Flow Line Map:  Immigration into the United States
Percentage of Total Immigrants per State

This week we got a lot of valuable practice in Adobe Illustrator as we constructed flow lines using the pen tool.  We also learned the principles of constructing proportionally-sized lines based on the values they represent.  In order for the lines to be reasonably similar in width (rather than gigantic vs. almost invisible), we can base their proportional widths on the square roots of the actual values, because the immigration values themselves cover a very large range.

It is important for this type of map a to have a strong figure-ground relationship so that the flow lines are emphasized.