You broke the code, I think.

More than once, the anti-immigrant people have succeeded a little too much, and actually gotten all the immigrants away from a given community / given state, and it’s created a big catastrophe for the economy and there was a ton of pushback until they made the immigration policy back less strict again (usually, by looking the other way on the hiring side exactly as you pointed out, but still being strict on the coming-into-the-country side, since trying to enforce that side is a lot less effective and basically just accomplishes short-term cruelty without doing much in the long term to stop people from coming in the country).