Harvard economist Ed Glaeser and former New York City Health Commissioner Mary Bassett were recently interviewed on national radio about COVID-19 and the future of our cities. What both of them touch on is the long history that cities and pandemics have had together, which is something that Glaeser also wrote about over here in City Journal. This pandemic isn't the first and it won't be the last.

Using history as an example, Glaeser makes the argument all of this can go one of two ways. After the influenza epidemic of 1919, cities rebounded quickly. The roaring twenties were one of "the great city-building decades in American history." But on the other hand, there's the Justinian Plague (circa 541 to 750 CE), which is thought to have played an important role in the fall of the Roman Empire. Glaeser argues that this plague, which took over 200 years to extinguish, is responsible for 800 years of de-urbanization across the Mediterranean. Is that so?

A quick search reveals that the impacts of the Justinian Plague are, of course, greatly contested. Some scholars have questioned whether it was actually an "inconsequential pandemic." Whatever the case may be, it doesn't change the fact that the modern world has been built around density and proximity. We are social beings and we are smarter and more productive when we are able to cluster together. That was the case in 750 CE and it remains the case today.