The U.S. is in the midst of a visa retrogression, when a surge in demand collides with annual caps, jamming up the processing queue. Experts estimate that at least 10,000 foreign nurses have been delayed indefinitely — a holdup that’s almost certain to worsen an already dire national shortage. After the pandemic led 100,000 nurses to leave their jobs due to burnout or early retirement, U.S. hospitals looked abroad to fill the gap.