Sublime

for a fully urbanized nation, we expect the growth rate for income on average to be nonzero and larger,

By growth we will mean that (modern) cities are typically characterized by fast change across many variables.

We have indeed focused on urban processes such as social interactions, mobility over space and time, active cost-benefit management, learning, and investment of resources and information toward collective production and exchange.

scale invariant, meaning that, on average,

who are assumed to want to maximize their utility10 U,

that knowledge, unlike labor or capital, is a nonrival quantity,

essence of cities is not space itself but rather the interplay between socioeconomic interactions, incomes, and transportation.

This balancing act requires agency and is implemented in diverse ways by individuals,

It is wider economic exchange between households and between firms for nonbasic goods that creates substantial GDP; such dynamics become necessary in cities,