A fundamental process at work in all urban environments is a deep division of labor and knowledge among people and organizations.

as speed increases so does distance, but that total time is much more conserved.

scale invariant, meaning that, on average,

(4) the larger settlements are, the greater the distance between them, with villages found more closely together than larger cities; (5) the larger the size of settlements, the rarer they become (i.e., there are many small villages for every large city); (6) larger settlements have more functions; and (7) they have more “high-level functions” such

This interpretation gives a mathematical correspondence between genetic evolutionary dynamics (in time) and neighborhood sorting (in space).

On the side of benefits, the best and most critical public goods and services—such

quantitative revolution in geography,1 a brief golden age during which researchers uncovered a number of famous empirical regularities that we will refer to as the “laws of geography.” These include Zipf’s law for the distribution of relative city sizes, the gravity law of flows between cities, Gibrat’s law of proportional city growth,

We will be able to tell how dense such cities would be, their amount of infrastructure, the heights of their skylines, how congested their transportation systems would be, how quickly an epidemic will spread, how often people meet, and how quickly they move!

we simply count these interactions as the value of the settlement