Sardines is a simple web app that I wrote to compare the density of Birmingham, Alabama to other cities in the world. This app shows you where the citizens must reside if our density was similar to another city. For example, if Birmingham, which has a low density, had the same high density as Paris, then the entire population would have to squeeze into just a small part of downtown.
Looking at density is a valuable tool when trying to understand why certain services like public transportation or retail struggle. Low density cities lead to car dependency, duplication of services, and long travel times.