In the campaign world, it is the United States that is now ruled by the IHA. While technically being a mutant isn't considered illegal yet, pretty much all of their rights have been removed. All federal/state buildings have mutant detectors and a mutant will be arrested for trying to go in there. In addition, most private establishments (grocery stores, other stores, restaurants, etc.) have mutant detectors and they will either not allow mutants at all or if you are a mutant jack up the prices incredibly. Also, any complaint about a mutant means they are automatically arrested, and trials, well let's just say that they are quick and always have the same results for mutants. The world for mutants is definitely like Germany during Hitler's early regime. No camps yet, but they definitely are in the near future.
As for leaving the United States, if you do not have a proper ID, you cannot get on a plane, boat, or go through the border, and of course mutants are not allowed to have IDs of this kind.