Just to pick an example like “PNW”, if you look at a city like, say, Portland, less than half (44%) of the residents are from Oregon at all.

https://worldpopulationreview.com/us-cities/portland-or-popu...

If you look at where people migrate from,

https://depts.washington.edu/moving1/Oregon.shtml

California and Washington are the major sources (of course!) but (1) California is not PNW, and (2) places other than CA/WA contribute many more migrants.