That incredible graphic is courtesy of The Pudding, using data from the Global Human Settlement Layer to show population density. The height of each line is proportional to the number of people living in the area. There are other high-density clusters in the world, but this view of the eastern US makes a point that I think a lot of people miss: not all cities are equally urban.
A good way to understand this map is to look at Ohio. There are four large cities in the state: Columbus at a bit less than 900,000 people, Cleveland at less than 400,000, Cincinnati at around 300,000, and Toledo a bit less than that. Akron and Dayton are both in the 100,000 to 200,000 range. None of these cities shows up on this map as having much height, meaning none are significantly dense. That may seem ridiculous if you’ve ever been in their downtowns, but the map data shows residential density. Most cities in the US have a dense commercial core surrounded by low-density residential areas. The commercial density doesn’t show here.
So the peaks in New York, Boston, Chicago, and a few other cities are based on apartment living. New York’s low rate of single-family house occupancy (the flip side of our high rate of apartment occupancy) means that the center of the city is that tall and wide peak of density. In Here is New York, E. B. White said that New York “is not Spokane multiplied by sixty, or Detroit multiplied by four.” Living in a dense city is simply different than living in a low-density one, and the size of the city does not matter. This is not a criticism of low-density cities: they exist, at least in part, because people like them. Atlanta is thriving and deservedly so, but has quite low density and is therefore a different urban environment than roughly-similar-sized Boston.
Finally, this issue can be illustrated by recent discussions of building a new generation of single-room occupancy residences, under the name “micro apartments.”
