And no small part of this is the fact that the 20th century Anglo economy emerged and thrived in an unusually stable global climate. The geographic expansion you describe was driven by the belief that the landscape would always be available, always be safe from natural disaster, well-watered, etc. Sprawl across the sunbelt all you like, there'll always be enough oil, water, land, wood, food.

By the 1990s it became clear that the 20th century was, on the whole, an anomalous period in the global climate, as scholars discovered the profound effects of things like the ENSO, or the centuries-long drought in the US Southwest that drove the Anasazi culture into collapse, a drought that may be reappearing.

But by that time it was too late; Anglo elites and enough of their voters agreed that the party HAD to continue, that the threats were too abstract or paranoid or "un-American" to be allowed to shape urban geography.

Now folks seem to be coming around and accepting reality, but the 30-year insistence that nothing was wrong has robbed us of the tools and political momentum to react properly.

And the world will live as one

Part of the US ethos of "getting government out of the way" fundamentally relies on geographical plenty.

Yes. The Turner Thesis in 25 words or less.  A convenient myth that has driven American expansionism for more than two centuries.  The irony is that Turner's thesis sought to explain why America was different from Europe, "the Old World," because we had an open frontier to expand into. In the last half century the mantra has become "Yes! You too can be like us!"  Well, the inconvenient truth is that you can't be like us.  Hell, we can't be like us any longer, now that that marvelous open frontier, with all those material resources "free for the taking," is gone.

We all bleed the same color.