published in the annotated projects of the IEEE VIS Arts Program.

Nature has its own ways of organizing information: organisms grow and register information from the environment. This is particularly notorious for trees, that in their rings, tell the story of their growth. The United States can be envisioned as a tree, with shapes and growing patterns influenced by immigration. The nation, the tree, is hundred years old, and its cells are made out of immigrants. As time passes, they are deposited in decennial rings that capture waves of immigration.

The paper and summary here