• Researchers at Northeastern University have visualized America’s immigration history as a tree trunk, with rings that delineate the waves and patterns in migration.
  • The colors represent groups of immigrants from different regions: Europe is green, Latin America is orange, Africa is red, Asia is pink, the Middle East is purple, and Oceania and Canada are blue.
  • In an animated version, the metaphorical tree trunk can be seen growing and evolving as the years tick by.

After more than 200 years of immigration, America’s population has evolved into a vast mosaic of nearly 330 million residents, whose ancestors hail from every corner of the world.

For researchers at Northeastern University, visualizing the nearly unfathomable magnitude and intricacy of the issue was a challenge that could only be symbolized by a living organism: the rings of a growing tree.

In a simulated dendrochronology, also known as the scientific method of dating tree rings, data visualization professor Pedro Cruz and journalism professor John Wihbey used the metaphor of tree growth to map out the country’s history of immigration using census data.

“The nation, the tree, is hundreds of years old, and its cells are made out of immigrants,” the researchers wrote. “As time passes, the cells are deposited in decennial rings that capture waves of immigration.

Those patterns and trends within America’s immigration history are clear from the colors and shapes of the rings — in the 1800s, immigrants almost exclusively came from Europe, represented on the tree by green dots.

Throughout the 20th Century, as more migrants came from Latin America, the tree rings skew southward and change to yellow dots to visualize the evolution. In more recent years, as Asian immigration has skyrocketed, the rings shift westward and the dots turn pink.

See an animation showing the last two centuries, showing the tree rings growing and evolving as the years tick by: