Palo Alto (păl´ō ăl´tō), 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.

Palo Alto, locality not far from Brownsville, Tex., where the first battle of the Mexican War was fought on May 8, 1846. American troops under Gen. Zachary Taylor defeated a Mexican force led by Gen. Mariano Arista, who retreated to Resaca de la Palma.