Portola Valley is an incorporated town in San Mateo County, California, United States. The population was 4,353 at the 2010 census. It was named for Spanish explorer Gaspar de Portolà, who led the first party of Europeans to explore the San Francisco Peninsula, in 1769. Portola Valley is one of the top forty wealthiest towns in the United States of America, with a median household income of $164,479 a year. Within the State of California, Portola Valley is ranked as the sixth wealthiest place.