Hundreds of thousands of migrants are being held in southern Mexico until US Election Day and are eager to rush border

TAPACHULA, Mexico — This town near the border of Guatemala holds a migrant time bomb ready to go off just after the US presidential election.The fuse was lit in December 2023, when the Kamala Harris-Joe Biden administration sent senior lieutenants to Mexico to work out the details of what remains a highly mysterious grand diplomatic bargain.Worried about what the optics of the southern border would do to their re-election chances — though not the migrant crisis itself — the White House wanted to stop the pictures of crowds of people gathered at the wall.The deal was to have Mexico deploy 32,500 troops to the US border to round up untold thousands of intending border crossers from the northern precincts and force-ship them — “internal deportation” by planes and buses — thousands of miles to Mexico’s southern provinces and entrap them in cities like Tapachula in Chiapas State behind militarized roadblocks.Mexico closed off most of its freight trains to migrant free riders, bulldozed northern camps, and patrolled relentlessly for more deportee targets.Meanwhile, the administration increased “parole” programs that flew migrants directly from countries like Venezuela, thus avoiding the border entirely.The effect was immediate.Illegal border crossings plummeted from embarrassing record-breaking 12,000-14,000 per day in November and December 2023 to about 3,000 or 4,000 per day before January was even over.But the crisis isn’t over.The just-released 2025 Homeland Threat Assessment from the Department of Homeland Security says that the decrease in illegal border crossing is largely due to “increased Mexican enforcement efforts.”What happens if that enforcement stops?Tapachula is bursting at the seams.No one really knows how many people are stacked up, but local shelter managers reported to me that they had filled up long ago.The publisher of Noticia De Tapachula, the daily newspaper, told me 150,000 immigrants were in town at any given time, a 42%...