San Mateo County Libraries | 1,049 followers on LinkedIn. Open for Exploration | San Mateo County Libraries is a Joint Powers Authority that comprises the cities of Atherton, Belmont, Brisbane, East Palo Alto, Foster City, Half Moon Bay, Millbrae, Pacifica, Portola Valley, San Carlos, Woodside, and the unincorporated areas of San Mateo County. We ignite growth through transformative experiences. It’s our mission to strengthen our community by creating an inclusive sense of place and environment for learning.