The United States isn’t quite a melting pot, this data visualization artist says. It’s more like a tree.

Assistant Professor Pedro Cruz recently won two awards at the Kantar ‘Information is Beautiful’ Awards. Photo by Matthew Modoono/Northeastern University

Pedro Cruz thinks of the United States as a tree. Specifically, as a tree trunk, with its concentric rings demarking growth throughout the years.

As Cruz imagines it, each ring, instead of being formed by the birth and death of new plant cells, is formed by the flow of new immigrants arriving to the country. By his reckoning, the United States would look like this.

Tree rings showing immigration for 1830 to 2016. Each dot corresponds to 100 immigrants.

Cruz, an assistant professor at Northeastern who explores new ways to visualize data, created this project as a way to illustrate centuries of immigration to the United States. He and a team of researchers collected individual responses to census questions from 1830 to 2015, so the visualization represents close to 3 billion individual data points, Cruz said.

“I wanted a way to celebrate the story of immigration that has been part of this country’s history,” Cruz said. “I liked this idea of modeling the visualization after a living organism, something that’s alive and still growing.”

Each dot on the image represents 100 people, and each color indicates the region of the world from which they originated. So, for example, the very center of the “tree” is mostly green, illustrating the wave of European migrants who moved to the United States.

Choosing the right way to illustrate this data was crucial. Cruz said he started with the idea of visualizing it in layers before refining those layers into tree rings.

“Immigration is part of the country itself,” he said. “It’s what this country is made of. Just like trees are made of cells, the United States is made of immigrants. The metaphor just made sense.”

Cruz also visualized the 50 U.S. states the same way, arranging each as it would appear on a map.

“A forest of trees,” he said.

A cartogram of tree rings for the 50 states, showing immigration and natural-borns. Each cell corresponds to 150 people.

For the individual states, he backfilled each ring with the natural-born population (in gray) in order to show the proportion of immigrants each year.

“I think the most evocative metaphors are the most familiar ones,” Cruz said. “We understand them immediately, and the viewer has that ‘a-ha’ moment.”

Cruz’s work appeared in National Geographic this year. And this month, he won two awards at the Kantar “Information is Beautiful” Awards, the data visualization equivalent of the Westminster Dog Show. He won gold in the “People, Language, and Identity” category, as well as the “Most Beautiful” award.

“That’s essentially Best in Show,” Cruz said.

Several Northeastern faculty and students helped in various stages of the project. They include Steve Costa, a graduate student in the College of Arts, Media and Design; John Wihbey, assistant professor of journalism; and Avni Ghael, a student in the College of Computer and Information Science. Additionally, Ruan Chao, of the Zhejiang University of Science and Technology, and Felipe Shibuya, an independent artist, contributed to the project.

For media inquiries, please contact