El Cajon, city, San Diego County, southwestern California, a suburb of San Diego; incorporated 1912. Products manufactured in the city include aircraft components, electronic equipment, and fabricated metal; productive citrus groves and avocado farms are nearby. Christian Heritage College and two junior colleges are here. The site of the city was part of Rancho El Cajon, an 1845 Mexican land grant. The city's name, Spanish for “big box,” is descriptive of its geographic setting in a boxlike valley. Population 73,892 (1980); 88,693 (1990); 94,259 (1998 estimate).