El Cajon, Spanish for “the drawer,” was first recorded on September 10, 1821, as an alternative name for sitio rancho Santa Mónica to describe the “boxed in” nature of the valley in which it sat. The name appeared on maps in 1873 and 1875, shortened to “Cajon,” until the modern town developed in which the post office was named “El Cajon.”
In 1905, the name was once again expanded to “El Cajon” under the insistence of California banker and historian Zoeth Skinner Eldredge.
According to the United States Census Bureau, the city has a total area of 14.4 square miles (37 km2), all land. It is bordered by San Diego and La Mesa on the west, Spring Valley on the south, Santee on the north, and unincorporated San Diego County on the east. It includes the neighborhoods of Fletcher Hills, Bostonia, and Rancho San Diego.