I have thought often about population density and the St. Louis area. I have NO expertise regarding these matters but as I think about my work in sustainability and construction the issue comes up, if only tangentially, regarding site selection, amenities and the walkability of a particular place.
I've read that Manhattan residents have very low carbon footprints. This is due to population density - at least in part. High rise apartments, smaller living spaces, fewer cars, highly walkable neighborhoods require less energy to maintain. Per the 2000 census New York City had a density of over 26,000 people/square mile. Manhattan's population per square mile was over 66,000.
There is a Wikipedia Article on Optimum Population. From the article: "The optimum population is the size of a population that is optimal. There are, however, various opinions on what "optimal" means in this usage, resulting in various end-targets for it, but estimations usually take ecological sustainability and carrying capacity more or less into account. Also, optimum population can refer to a specific area, such as a region or country, but can also refer to the entire world or universe."
According to the 2010 census St. Louis has a density of just over 5,000 people per square mile.
Here is a chart of our region:
Having seen films like The Pruitt-Igoe Myth in which the plight of high density developments in shrinking cities is shown to be problematic I wonder: How do we find an equilibrium? What is our equilibrium? How would a region keep this dynamic thing balanced over the course of time?