For much of the Biden administration’s first three years in office, migration surged at the Mexican border. Administration officials frequently argued that the problem was beyond their control — a reflection not of U.S. policy but of global forces pushing people toward the border.

Then, starting in December, when the issue threatened President Biden’s re-election, he began a crackdown. The traffic of people crossing the border plummeted. Today, it remains near the lowest point since 2020 and not so different from levels during parts of the Trump and Obama administrations. This week, the Biden administration imposed tough new rules to keep it that way.