Clusters of smart people of the highly educated sort that economists refer to as “human capital” are the key engine of economic growth and development. The standard way economists measure this is to take the percentage of people in a country, state, or metropolitan area with a bachelor’s degree or higher. Jane Jacobs argued that the clustering of talented and energetic in cities is the fundamental driving force of economic development. In a classic essay, “On the Mechanics of Economic Development,” the Nobel prize-winning, University of Chicago economist Robert Lucas formalized Jacobs’ insights and argued that human capital, or what can be called Jane Jacobs externalities, are indeed the key factor in economic growth and development. Still most scholars measure human capital in terms of population, not in terms of its geographic concentration.
So I was intrigued by this fascinating analysis by Rob Pitingolo (h/t: Don Peck) which takes this question head on. To get at the issue of human capital clustering, Pitingolo compiled a neat measure of what he calls “educational attainment density.” Instead of measuring human capital or college degree holders as a function of population, he measures it as a function of land area – that is, as college degree holders per square mile. As he explains: