why did California grow for so long in terms of population?

[Linus Van Pelt]

Ever since World War II there has been significant migration out of the northeast and Great Lakes to warmer and more suburban areas with job growth and affordable housing, whether to California or to the South. But in the postwar decades the South had two major disadvantages that it no longer has: one was that its economic prospects and national image were hampered by racial tension and the various conflicts arising from the decline of the old segregated system. The other was that air conditioning, though available, was more of a luxury then and not standard in middle-class housing, so California's relative climatic advantage was more important. Conversely, California has now developed a major disadvantage of its own in the high cost of living that others have mentioned.

Demand for living space in the California coastal metros is still very high: that's why it can stay so expensive. Lots of people would move there if they could afford it. It is really a supply issue. The population growth of the south indicates high demand and adequate supply, while the high prices of the northeast and Pacific coast indicate high demand but constrained supply. It's mostly only in the rust belt and certain rural areas where you get the combination of low population growth despite low prices that indicates low demand. And the supply thing, in California, is complicated: part of it has to do with geography, but a lot of it has to do with zoning policies as well.