CHICAGO — Tens of thousands of Chicago students, parents, and teachers learned Thursday their schools were on a long-feared list of 54 the city plans to close in an effort to stabilize an educational system facing a huge budget shortfall.

Mayor Rahm Emanuel says the closures are necessary because too many Chicago Public School buildings are half-empty, with 403,000 students in a system that has seats for more than 500,000. But opponents say the closures will further erode troubled neighborhoods and endanger students who may have to cross gang boundaries to attend school. The schools slated for closure are all elementary schools and are overwhelmingly Black and in low-income neighborhoods.