Nextstrain

As the Library of Congress archives visuals about coronavirus, it is documenting a dramatic expansion in the forms and functions of maps — and their makers.

This interview is adapted from the latest edition of MapLab, CityLab’s biweekly newsletter about maps that reveal and shape our urban spaces. Sign up for the newsletter here.

The 5.5 million-plus maps at the Library of Congress in Washington, D.C. are so many windows into history. With items from the 13th century to the modern day, the world’s largest repository of geospatial data is always growing, with its keepers on constant lookout for new additions.

Lately those librarians have had their hands full. John Hessler, a specialist in modern cartography and GIS at the Library of Congress, is collecting the maps of the coronavirus pandemic. In a public health crisis where the interpretation of data, maps and other visualizations has been critical, Hessler’s job (at least part of it) is to ensure that future historians and lawmakers can access that data, and see how mapmaking itself advanced, as they try and grasp this moment in time.

I spoke to Hessler over the phone; our conversation has been condensed and edited for clarity.

Being a map librarian must come with its challenges even under normal conditions, considering the volume of digital maps out there these days. What’s it like?

The field has just exploded. It used to be that mapping was the exclusive subject area of governments and some private companies that published maps, which means that the maps we collected were limited but generally more accurate. Now a lot of amazing cartography is coming from people sitting in their offices, cafés, and at home, visualizing geospatial data in ways that early cartographers couldn't have imagined. Sometimes maps come out that just blow you away, like this wind map. It was just the perfect symbol of what cartography has become now: using geospatial data to visualize the world in a dynamic way.

A screen-grab of a dynamic map of wind patterns over the U.S. during Superstorm Sandy. (HINT.fm)

That’s the other thing that has changed. We used to collect maps or 3D models that were static, easy to reach out and grab. But now we often gather data as opposed to the map itself, as mapmakers look at more dynamic phenomena, whether it's storms or Covid-19 or the processes of urban change. Those maps make people like me so excited about where we are and where we’re going. But also it’s harder for us to keep track of who is doing what and how to preserve it.

How do you preserve the dynamic maps coming out of the pandemic, while it’s still unfolding? I’m thinking about the maps changing hour-by-hour from the Johns Hopkins Coronavirus Resource Center, which are a go-to for many people right now.

It’s not easy. It kind of comes down to what’s available and what you can grab. Right now, I am making lists, reaching out to people who are involved in the pandemic mapping as we speak, and capturing things that are of great interest, like some of the phylogenetic mapping of the disease that’s going on. That is really new and fascinating but still fits into the tradition of disease and epidemic mapping that started in the 19th century.

A global sample of genomic mutations of novel coronavirus, charted by evolutionary group over time. (Nextstrain)

For example, a project called Nextstrain is geo-spatializing the mutations in the Covid-19 genome as nucleotides are passed from human to human. That is a brand new approach that has exploded in this pandemic, and it is just a beautiful way to visualize this thing: You can see how New York City’s strains really come from Europe, while the ones in Washington state are largely from China.

A map how of different strains of the novel coronvirus have spread around the world. (Nextstrain)

We’re also looking at cell phone tracking apps and how transmission analysis is being done with those, and if the data will be useful. Sometimes we’ll just collect snapshots of what we are doing now, which would be nice for people in the future to know was happening.

Some of it also reflects the cultural experience of the pandemic, like some of the social media mapping that’s going on: People are using machine learning to map where certain misinformation is coming from based on tweets, as well as sentiments about lockdowns. We’ve come so far in deep learning tools, and the maps coming out of this disaster really show that.

One of the defining features of this pandemic is the tremendous uncertainty about the future and the lack of clear data to tell us for sure where things are headed. How have you seen that reflected in maps? Have maps misguided us at times? How have they played into the emotional experience?

What you’re asking really goes to the power of maps: What a map does is take a complex situation, abstracts it from the reality on ground and presents a simple image to help people try and understand what’s happening. And like any produced tool, maps have particular ways of placing ideologies, conscious or subconscious. That can include what color they chose: for example, those Johns Hopkins maps use gigantic red dots on a black background, which from a design perspective just explodes off the page. There are also a couple mapping places that have been giving grades on how well places are doing social distancing. So if you see a county with an explosion of color and a D minus, that might freak people out because you’re only looking at this image that’s aggregated and the people who made it decided on what’s good and bad, without much context about what came before.

Have members of Congress been requesting maps or assistance from you recently?

There have been requests, but I can’t say what because there is confidentiality about anything that’s being borrowed. A library just doesn’t say what particular people have pulled. The Congressional Research Service has its own GIS and mapping group, and they've been very busy with this sort of work.

I’m just amazed at the sheer volume of geospatial images. It’s really an historic mapping moment like no other I remember.

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