Palo Alto (pălˈō ălˈtō) [key], city (1990 pop. 55,900), Santa Clara co., W Calif.; inc. 1894. Although primarily residential, Palo Alto has aerospace, electronics, and advanced research industries. A local attraction is "El Palo Alto," a tree that is more than 1,000 years old. Nearby Stanford is the seat of Stanford Univ.