Cripple Creek, Colorado grew from ~500 to 50,000 people in under a decade (1891–1900), despite two fires in 1896 that burned down a third of the town.
The catalyst for this growth was the gold rush, but it proved we can build new towns relatively quickly even despite major disasters.
When was the last time a town of 50,000 was built from scratch in North America? Why have we seemingly stopped trying?