Brownfield is a form of greenfield. It just has to be greened first. The contrast is between greenfield and infill, and greenfield is much, much, much easier to develop at scale. 1/

See the history of San Francisco, or Houston for that matter. You get fast, near-in growth for as long as there are near-in greenfields. Then, suddenly, it stops. 2/

You are left with sprawl dominating, because infill is hard and we unfortunately don’t regulate to ensure that outward expansion is dense. Eventually sprawl self-limits, as distance overwhelms the pull of urban amenity, and even the Houstons stop growing. /fin