The city of San Francisco is facing increased security risks as its aging libraries struggle to keep pace with a rapidly growing number of visitors and the increasing popularity of digital video streaming services.
The city is one of only two major U.S. cities that do not require public libraries to wear face-covering veils, the other being New York City, where the practice is common.
But some libraries have also begun to tighten security measures.
In recent months, the city has added more security cameras, installed cameras that capture footage and installed a facial recognition system that will alert library workers if they spot suspicious activity, according to a report in The Los Angeles Times last month.
In October, the libraries also ordered security cameras at their entrances and removed metal detectors from the lobby, the report said.
In addition to the more frequent security screenings, libraries have begun requiring visitors to wear a face-mask, which would not be required in San Francisco, where most visitors wear a mask.
The new policy is intended to provide a better image of the library to staff and patrons, the Los Angeles City Councilman José Huizar said.