San Mateo Coonty is includit in the San Francisco-Oakland-Hayward, CA Metropolitan Statistical Area, an is pairt o the San Francisco Bay Area, the nine coonties borderin San Francisco Bay. It covers maist o the San Francisco Peninsula. San Francisco Internaitional Airport is locatit at the northren end o the coonty, an Silicon Valley begins at the soothren end. The coonty's built-up auries are maistly suburban wi some auries bein vera urban, an are hame tae several corporate campuses.