Dendrochronology of U.S. immigration

Immigrants are central to the identity of the United States, the population of which has grown in number and diversity as a function of new arrivals from around the globe. This article describes a visualization project that uses the visual metaphor of tree rings to explore the contribution of immigrants to the country’s population. Immigrants and native-born persons are represented and differentiated as cells in trees, with layered annual rings capturing patterns of population growth. These rings register, in their shape and color, certain environmental conditions. In order to mimic the natural process by which growth rings are formed, we devised a computational system that simulates the growth of trees as if cells were data-units. Dendrochronology involves dating certain events by analyzing patterns of growth in trees. Analogously, in our visualizations the rings can be counted and dated, showing the chronological evolution of the population. The dendrochronology theme is a poetic take on the data, yet it is also a functional and conceptual space that is used to construct language and rationales on that data. The tree-growth process not only inspires the appearance of the visualizations but also informs the rules of the computational system that creates them.