The new evidence suggests that unauthorized migration across the southern border has plummeted, with successful illegal entries falling from roughly 1.8 million in 2000 to just 200,000 by 2015. Border enforcement has been a significant reason for the decline — in particular, the growing use of “consequences” such as jail time for illegal border crossers has had a powerful effect in deterring repeated border crossing efforts. The success of deterrence through enforcement has meant that attempted crossings have fallen dramatically even as the likelihood of a border crosser being apprehended by the Border Patrol has only risen slightly, to just over a 50-50 chance.