 Until the 1950s, however, much of the San Mateo County coastal area remained sparsely settled and the few surviving communities were relatively small.With the dramatic rise of housing costs along San Francisco Bay (with average prices over $1 million in 2008), there has been greater incentive to build along the Pacific Ocean, resulting in the steady growth of Montara, Moss Beach, El Granada, Half Moon Bay, and Pescadero.This has done little for Purissima, which had long since vanished.