Back when the enforcers were called "ICE", there were many anecdotes on self-deportation. Two of my favorites were (as reported in Texas newspapers):
A green helicopter flew low over a development of tract homes under construction. Panic among the illegals ensued, with many in the neighborhood jumping in cars and hauling posterior. It turned out the promoter had hired a helicopter to do a fly-over to show off the site to potential investors.
Late Saturday night at a big city ER was unusually quiet, hardly anyone showed up. A staff member stepped outside for a smoke and saw a green van illegally parked in front of the ER. Evidently the illegals thought it was La Migra and stayed away in droves. Thereafter, the running joke there was that when the staff wanted a break, they should park a green van out in front.
Now imagine the modern day equivalent of those green vans throughout a post-Cruz or -Trump America.
Enforcement has worked everywhere it has been tried.
Alabama and Georgia saw illegals flee with just the passage of laws, before any enforcement had taken place.