Just read of a case of an illegal alien who worked in a town in Michigan for years using a fake Social Security number. He was a serviceman at a garage. His troubles began when his boss retired and offered to sell him the business. He had paid cash for the house but when he tried to buy the business the mortgage company found his background did not check out. He was outed.
He and his wife were to be deported. Their children were born in the US and could stay. Many years a tax paying citizen, a good neighbor, a productive member of the town but...
Tough call when there are thousands of criminals wandering around every large US city with no intention of ever contributing anything but chaos. On the other hand, someone else who abides by the law and follows the rules is still waiting to get into the country.
M