The Potrero Branch Library is a public library that serves more than 800.000 residents in the city of San Francisco, in northern California. It is an affiliate branch of the San Francisco Public Library (SFPL), founded in 1879 in a rental space with 6,000 books. In response to the escalating demand for library services, the Potrero Library, the 22nd branch, was founded. Potrero has been through so many changes, from its closing in 1902 to a temporary library station moving to different locations, until it was finally opened to the public again in 1951 and renovated in 2010. Today, it contributes to the county system's entire resources, which include more than 2.6 million books and serial volumes, more than 83,000 e-books, nearly 110,000 audio files, and more than 240,000 video files. Furthermore, there were more than 426,000 registered borrowers, nearly 11 million items circulated annually, and more than 420,000 people visited the library system each year in all 28 sites.