Module 9: Flowline Mapping



The purpose of this lab was to explore the design concepts involved with flowline mapping. For this lab, I used Adobe Illustrator to create a flowline map of immigration to the U.S. using data from the U.S. Department of Homeland Security. 

I chose to create my flow map where the choropleth map of immigration per U.S. state is overlaid on the world map. I chose this option because it saved space on the map layout. In addition, I preferred keeping the continents in place to more accurately show the layout of the world and its relation to immigration to the U.S. (although the map does not aim to show the actual paths of immigration, just the percent from each region). I also chose this option because shows where the U.S. is located in relation to the other regions. Even though this option made it slightly more difficult to see the choropleth map, enlarging the whole map made the choropleth map easier to see.

I then created proportional flowlines from each region to the U.S. so as not to conceal other map features. I calculated the proportional widths of the flowlines using an equation in Excel. In addition to sizing each flowline proportionally to the total immigration from each region and making the lines a dark shade of blue, I applied drop shadows to the flowlines. I used a drop shadow to highlight this feature as it is the focus of the map and to put them at the top of the visual hierarchy. I also changed the colors of the regions to different light shades of green so that they could be distinguished from each other but also so as not to overshadow the other features of the map, i.e. reduce their impact in the visual hierarchy. I left the choropleth map in place over the U.S. and didn’t change the colors in order to also draw attention to this area, i.e. increase the impact in the visual hierarchy. 


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