San Diego city is in Southern California.
San Diego ( [ ˌsæn_diːˈeɪɡoʊ ] , Spanish for `` Saint Didacus '' ; Spanish : [ san ˈdje.ɣo ] ) is a major city in California , United States . It is in San Diego County , on the coast of the Pacific Ocean in Southern California , approximately 120 mi south of Los Angeles and immediately adjacent to the border with Mexico . San Diego County is a county in the southwestern corner of the state of California , in the United States . Its county seat is San Diego , the eighth-most populous city in the United States . Southern California . The Los Angeles area has over 12 million inhabitants , while the Riverside-San Bernardino area has over 4 million inhabitants and the San Diego area has over 3 million inhabitants .