El Monte (ĕl mŏnˈtē) [key], city (1990 pop. 106,209), Los Angeles co., S Calif.; inc. 1912. A residential, industrial, and commercial city in the San Gabriel Valley, El Monte manufactures furniture, electronic equipment, semiconductors, chemicals, and plastic and metal products. The population has increased by more than 40% since the 1970s, diminishing the walnut groves the city is known for. El Monte was founded in 1852 by westward-bound pioneers on the Santa Fe Trail.