“The largest wave of immigration in history from a single country to the United States has come to a standstill,” declares an authoritative new study from the Pew Research Center. “After four decades that brought 12 million current immigrants — most of whom came illegally — the net migration flow from Mexico to the United States has stopped and may have reversed.”

It’s a trend experts have suspected for quite a while, but look for the new report to become a major point of contention in the immigration debate. Advocates of comprehensive immigration reform — known as amnesty in some conservative circles — will make an argument that boils down to this: The problem is over. We don’t need to keep beefing up border security and spending millions on enforcement. Now, we can get to work on a “path to citizenship” for millions of illegals.