The States have authority over the Ports of Entry. They could walk into my office to day and shut us down.
That's not to say the s**t would not hit the fan, but we would comply and let Washington deal with it.
Just like they may have jurisdiction over a post office when a state crime has occured there. Immigration laws, which are ONLY promulgated by congress by way of the consitution, ARE NOT VIOLATIONS OF STATE LAW.