There is an interesting study by Rob Pitingolo showing the density per square mile of residents with college degrees. He suggests:
The theory that there is economic value to having smart people together rests on the assumption that smart people collaborate with each other. You could have a whole bunch of smart people in one place, but if they don’t interact with each other, what’s the value?
That’s why I propose we start using educational attainment density, measured as college degree holders per square mile.
In short, he suggests that the density of smart people determines the level of their interaction, and, therefore, the evolution, advancements, and culture of that community itself.
Here are a couple of interesting charts he presents:
The real estate tie-in is this? How much does the theory of higher levels of smart-people interaction justify San Francisco’s high real estate prices?