Somewhat unrelated, but several states have seen unexpected growth since that time period
Kind of hard to believe, but in 1950 Florida and Kentucky had about the same population. Since then Florida has 8x'ed (I think because of modern AC). Other states (especially in the south and southwest) have seen similar levels of growth to CA. I don't see how the problem you mentioned is specific to California
https://en.wikipedia.org/wiki/1960_United_States_census
https://www.vox.com/2015/6/27/8854037/us-population-history-...