Calexico is a city in Imperial County, California. The population was 38,572 at the 2010 census, up from 27,109 at the 2000 census. Calexico is about east of San Diego and west of Yuma, Arizona. The name “Calexico” is a portmanteau of California and Mexico, which, like that of its adjacent sister city of Mexicali, emphasizes its identity as a border city.