Greyhound bus stations. If you’ve ever taken a bus across country before, they pick up a lot of people at prisons and they stay on until some west coast city (LA, SF, Portland, or Seattle). That accumulates, and once they stick around for at least a year, they are considered resident (for some definition of housing lost, that means even if they were housed in a hotel once, or couch surfed at the start). Surveys that rely on self reporting are incredibly inaccurate. One was done in Seattle, and found out that 80% of King county’s homeless population was previously housed in pioneer square, an absurdity that put the entire survey in doubt.

It really is in the self interest of homeless oriented agencies and NGOs to present the problem as local as possible. If it isn’t local, then giving out housing will only make the local problem worse (people will start arriving for their free housing from other areas of the country), you can judge your success by how much worse the problem gets, which isn’t popular with local voters.

Without good information, at any rate, it isn’t weird that we are seeing the problem get worse for every billion we throw at it. Eventually the popular cities will just give up trying very hard because they never had the power to fix it in the first place.