The narrative that most homeless people in SF come there from other places is contradicted by data. In annual surveys, ~70+% of people who are homeless in SF lived in SF when they became homeless.
there's a lot of issues with the methodology in this cluster of surveys. for one it's entirely self-reported, and furthermore it only asks where they were staying immediately prior to becoming homeless. digging further into cases you see people who come here and live in an rv for a month or crash in their friend's garage, before ending up on the streets and counted here as a local resident. studies which take into account longer history and context tell the same story.
I've gone back and forth on how I feel about self-reported data like that.
If you're homeless and moved to a particular city because you believe you'll have a better time there, then you might feel incentivized to claim that you originally lived there before becoming homeless.
Unfortunately there's no good way to confirm or refute this data.
There are also lots of reasons to question exactly how such numbers are determined and what they really mean, which is a long discussion I don't care to have.
Due to the temperate weather, California has largely become the dumping ground for America's chronic homeless.
Not all homeless are chronic homeless.
You don't need all your homeless to be chronic homeless to dramatically and negatively impact the scale of the issue for one state that has, iirc, 12 percent of the US population and 25 percent of the US homeless population.
if we didn't have such a huge issue with out of state people swelling our homeless population, we wouldn't have such programs as these to repatriate them: https://www.sfexaminer.com/news/housing/homeward-bound-reloc...