Southern California, often abbreviated as SoCal, is a megaregion or megapolitan area in the southern portion of the US state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The region generally comprises California's southernmost 10 counties, stretching along the coast from about San Luis Obispo County to the United States and Mexico border, and from the Pacific Ocean inland to the Nevada and Arizona borders. The heavily built-up urban area stretches along the coast from Ventura, through the Greater Los Angeles Area, the Inland Empire and down to San Diego. Southern California is a major economic center for the state of California and the United States.
Southern California's population encompasses eight metropolitan areas, or MSAs: the Los Angeles metropolitan area, consisting of Los Angeles and Orange counties; the Inland Empire, consisting of Riverside and San Bernardino counties; the San Diego metropolitan area; the Bakersfield metropolitan area; the Oxnard–Thousand Oaks–Ventura metropolitan area; the Santa Barbara metro area; the San Luis Obispo metropolitan area; and the El Centro area. Out of these, three are heavy populated areas: the Los Angeles area with over 12 million inhabitants, the Riverside-San Bernardino area with over 4 million inhabitants, and the San Diego area with over 3 million inhabitants. For CSA metropolitan purposes, the five counties of Los Angeles, Orange, Riverside, San Bernardino, and Ventura are all combined to make up the Greater Los Angeles Area with over 17.5 million people. With over 22 million people, southern California contains roughly 60% of California's population.
To the east of southern California are the Colorado Desert and the Colorado River at the border with the state of Arizona and the Mojave Desert at the border with the state of Nevada. To the south lies the international border with Mexico, and to the west lies the Pacific Ocean.