> What is not clear to me from the article is what data they are getting from CMS

They’re literally just pulling up addresses (404 Media). Replace Palantir with McKinsey and making an app for VLOOKUP makes more sense.

I get that - the question is why CMS would have addresses for undocumented immigrants at all (assuming for the moment it is only undocumented that they are looking for). Undocumented immigrants are not eligible for Medicaid, so how and why would CMS have their names and addresses?