For twenty-five years, the airport gate stood as one of the quiet monuments to September 11 — a boundary drawn in grief and caution that separated families at the terminal door rather than the boarding threshold. This week, as the nation marked the anniversary of the attacks, the TSA began allowing non-ticketed visitors to pass through security and accompany travelers to the gate once more, restoring a practice so ordinary before 2001 that it had no name until it vanished. The change is modest and conditional, but it asks a question that grows more pressing with each passing year: which post-9