A cartogram is a map in which a variable of interest (e.g. population, income) is substituted for area. In this case, we've taken the population of each US state as determined by the census, conducted every decade. The animation below illustrates high-level trends that have happened in the United States over its lifetime, such as a general migration westward. Click "Replay" on the left side in order to watch the animation again, or click any of the year labels on the right to navigate directly to a certain year.