How did you decide on your map subject for the Migration atlas?
Deciding what to map was the hardest part of the Atlas in a Day experience. The first night, we developed a number of interesting concepts but nothing felt quite right. Were data available? What interesting story would we tell? Did the content actually matter?
With time and adult beverages[1] dwindling rapidly, we decided to keep our migration map local to narrow our options. Both of us are transportation planners and regularly make maps in Seattle, so we’re familiar with the local data, unique cartographic challenges, and transportation issues (after all, migration is transportation).
By midnight, we had considered mapping salmon migration, peak hour bus ‘migration’ to and from downtown, and tech worker migration to gentrifying neighborhoods. These were interesting and challenging concepts, but – in the grand scheme of things – still felt less than ideal for the Atlas in a Day challenge.
We finally settled on a map that merged ecology, climate change, transportation, and land use planning: the migratory impacts of sea level rise in Seattle’s Duwamish Valley. We knew data were available, were genuinely invested in the product and its message, and were both excited about visualizing the information in a vivid way.
The East Duwamish Waterway, looking north towards downtown Seattle
We chose to map sea level rise and the migration of people and jobs from the Duwamish Valley because it is one of the most vulnerable communities on the Puget Sound. A significant portion of the developed land in the Duwamish Valley is former intertidal zone that is now home to commercial and industrial family-wage jobs, as well as lower-income residential communities. Because much of the area is landfill, critical infrastructure in the SoDo (South of Downtown), Georgetown, and South Park communities is very close to sea level, placing it within the zone likely to be inundated by sea level rise. For residents of these neighborhoods, the anticipated change in sea level compounds environmental injustice: the Duwamish Waterway is a superfund site located in an inversion zone where pollution settles from nearby air, road, water, and railways.
The West Duwamish Waterway, looking south
What was your mapmaking process?
We split the work between the two of us. Joe focused on gathering data, developing an ArcGIS layout of the information, and conducting statistical analysis in R on the number of jobs and people that would be displaced with each additional foot of sea level rise. Brendan took the data out of GIS and developed the color palette, symbology, legend, and other cartographic elements of the final product in Illustrator. Brendan also designed and produced the data visualizations included with the legend. We worked together to define a map extent and determine what key geographic elements should be included in the final product.
We designed our workflow so we could work simultaneously, without wasting time waiting for one another to complete tasks or finalize assumptions – after all, we only had one day! As an example of this workflow, Brendan set up a basemap, decided on colors and fonts, and designed labels while Joe analyzed various sea level rise scenarios. It ended up being a remarkably efficient process and one we’ve continued using professionally.
What surprised you during the map-making process?
For us, one of the most surprising findings was how vulnerable jobs were, relative to dwellings. In hindsight, this makes perfect sense, given how many large worksites are located in the Duwamish Valley. We had initially assumed, however, that the residential communities of South Park and Georgetown were more populous than our data sources showed them to be. We should note, as well, that the Duwamish Valley is home to a large number of people experiencing homelessness, who may not have been accurately counted in the American Community Survey population estimates.
We were also surprised (and very excited) to learn how much we could accomplish in 24 hours. Our skills complemented each other in a way that made the process easy to streamline.
How do you hope this map might affect people?
At the end of the day, we hope this map raises awareness of the human and economic impacts of climate change. We think the special power of cartography – which can communicate massive amounts of information in small spaces – can help people understand and visualize these impacts.
It's also worth noting that we produced this map from free, publicly-accessible data. Anyone with GIS and design aptitude can recreate this map for places near and dear to them.
[1] This Atlas in a Day brainstorming session was unofficially sponsored by the Duwamish Valley’s Machine House Brewing.