Are you a U.S. citizen?
Every interview I have had has asked this. Even pre-interview screening includes this question. Is it really illegal for them to ask this?
Note: Not really permissible on this site, but what would a good reply to such a question be if asked during an interview and you know that "the wrong answer" means no continuation interview?
To the people who are not in the job-search mode. The typical question asked are verbatim,
"Do you have the legal right to work in the US?" — which I believe is legal.
"Do you now or in the future require a work visa to continue to work" — which is a round-about way to ask about citizenship because non-citizens are the only ones who need the work visa.
CLARIFICATION: Since people are misunderstanding my use of CITIZEN. I am referring to any individual who has the same employment rights as a citizen as a citizen, this includes people who are PR's(green card) or citizens, or hold permanent authorization to work in the US (O-1 etc).