imho if I were dictator of California I would figure out how to safely build a supercity based on the parts of Sonoma County that are geogically sound.
Weather is the best here in the world + if we were really green/efficient- we would be building in places that require minimal inputs (power+water).
Worst places+most inappropriate in the US to build big cities: Florida, Texas, Nevada. Eastern seaboard. Illinois. Pennsylvania
Might take 100 years for ppl to figure this out.