Proportional Flowline Mapping

This week's lab assignment turned out better than I had feared. My task was to create a proportional flowline map showing the relative proportion of immigration to the U.S. from various parts of the world, but I had to do all my work entirely within Adobe Illustrator. Fortunately, we were provided with a basemap in .ai format, which had layers prepared in good order, so I did not have to worry about interpenetrating features like I've encountered in the past when I've exported to .ai format from ArcGIS.

The flow of immigration is depicted in the map below by arrows that are sized proportionally to the relative amount of immigrants that entered the U.S. in 2007 from each continental region (excluding Antarctica). The proportional width of the arrows was based on the square roots of the immigrant population (thus tempering the proportional differences, else the difference between Asia's immigrant population and Oceania's would have been two orders of magnitude rather than one).

2007 Immigration to the United States