Bring back the chain-gangs ... any IA over 16 years old gets one year at hard, back-breaking labor and then sent back South. If caught in the USA again, they do two years and then get sent back South. If caught a third time, hang ‘em from the Trump wall and leave the carcass for the buzzards.
It won’t take long for the message to filter down to even the lowest IQ that you need to start your American experience at the USA embassy.
Nothing will change unless the consequences are severe.
We still have that in my County for County jail inmates. They aren’t chained but they are in striped uniforms with an armed deputy following them in a truck. I saw one group that had yellow placards on their backs that told what they were doing time for. For example “I was driving drunk” or “I was arrested for theft”, stuff like that.