What Micro-Mapping a City's Density Reveals

Density is one of the most important urban characteristics. A high-density city like New York looks, feels, and functions differently than a low-density city like Des Moines. Yet the textures of density within a single city can be just as varied as average densities between cities. Pockets of intense concentration or islands of relatively thin settlement sometimes bear little resemblance to the overall density of an urban area.

Since most people experience a city at the scale of a neighborhood or district, rather than the scale of metropolitan regions, paying attention to these fine-grained variations in urban form is more useful than broad-stroke statistics for understanding the everyday realities of population density. A new visualization I’ve put together helps picture these local patterns by examining density in American cities one square kilometer at a time. (Technically, these rectangles are 30 arc-second cells, which are roughly, but not exactly, one square kilometer.) This perspective lets us drill down to the micro-geography of density in American cities, with oftentimes surprising results, as in the densest grid cell of greater Salt Lake City (below), which isn’t high-rises but mobile home parks.