About San Mateo County, California
San Mateo County is a county located in the U.S. state of California. As of the 2010 census, the population was 718,451. The county seat is Redwood City. The county’s name is derived from the Spanish pueblo of San Mateo de Alta California, named for Saint Matthew.
San Mateo County is included in the San Francisco-Oakland-Hayward, CA Metropolitan Statistical Area, which is also included in the San Jose-Sunnyvale-Santa Clara, CA Combined Statistical Area.
The county covers most of the San Francisco Peninsula. San Bruno Mountain rises at the northern end of the county and several smaller hills dot the southern peninsula. A coastal plain several miles wide lines the shores of San Francisco Bay, and is crossed by many urbanized valleys extending inland from the bay, including the cities of San Mateo, Redwood City and Menlo Park.