In reality it is probably double or triple that.

I used to be a data analyst for a non profit assisting the homeless.

650k comes from the Point In Time, PIT count.

There is 0 consistent or established methodology for how to actually do the count across the country.

Every government agency and non profit in every city and county does it differently, and then it all gets amalgamated in inconsistent ways at multiple stages, by multiple different agencies.

Does living in a car or RV count as homeless?

Does jumping from motel to motel because you have an eviction and can't rent anywhere count?

Does living in a managed tent city or tiny home community count?

Sometimes yes, sometimes no, for all those.

Are you currently living in a shelter, which may or may not only allow you to stay inside during evenings, regardless of inclement weather or your disabilities, and lock you out if you arrive late, which almost certainly will kick you out after 30 or 60 or 90 days, regardless if you've found a home or not?

Not homeless.

Beyond stuff like that... what, do people think that teams of demographers go around and personally locate and record every single homeless person in the country?

Fuck no, they count the people at the most stationary, most visible, least dangerous encampments.

...

The way I estimate its two or 3 times the PIT count is from the number of requests we got for assistance we literally didnt have the resources to provide, and then scale appropriately.

Its as methodologically sound as the PIT count.

That's closer to 'does not have a permanent residential address capable of receiving mail.'

...

Try setting up a (non prepaid) phone plan, replacing a stolen ID, setting up a debit card or SNAP account without a permanent residential address capable of receiving mail.

99% chance you can't.

Try getting an apartment with no previous address whatsoever for 2 or 5 or 10 years, god knows what kind of credit score.

99.99% impossible.

...

EDIT: When they say migrants, they don't mean foreign migrants, from other countries, exclusively.

Its mostly internal migrants. American, homeless citizens, who just get round up and shipped to somewhere Republicans are not in charge of.