Los Altos Listen/lɔːs ˈæltoʊs/ is a city at the southern end of the San Francisco Peninsula, in the San Francisco Bay Area. The city is in Santa Clara County, California, United States. The population was 28,976 according to the 2010 census. Most of the city's growth occurred between 1950 and 1980. Originally an agricultural town with many summer cottages, Los Altos is now an affluent bedroom community. Los Altos has several distinctive features.