Southern California Southern California is a megaregion , or megapolitan area , in the southern area of the U . S . state of California . Large urban areas include the Los Angeles Metropolitan Area , the Inland Empire , and Greater San Diego . The region stretches along the coast from about Santa Barbara 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 , 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 , or MSA , areas : Los Angeles County and Orange County together make up the Los Angeles metropolitan area ; the Inland Empire consists of Riverside and San Bernardino Counties ; the San Diego metropolitan area ; the Bakersfield metropolitan area ; the Oxnard - Thousand Oaks - Ventura metro 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 . With combined surface area of 56 , 512 sq mi , southern California alone is bigger than England . Significance . Within southern California are two major cities , Los Angeles and San Diego , as well as three of the country ' s largest metropolitan areas . With a population of 3 , 792 , 621 , Los Angeles is the most populous city in California and the second most populous in the United States . Just to the south and with a population of 1 , 307 , 402 is San Diego , the second most populous city in the state and the eighth most populous in the nation . Its counties of Los Angeles , Orange , San Diego , San Bernardino , and Riverside are in the top 15 most populous counties in the United States and all five are the top 5 most populous counties in California . The region is also home to Los Angeles International Airport , the second - busiest airport in the United States by passenger volume ( see World ' s busiest airports by passenger traffic ) and the third by international passenger volume ( see Busiest airports in the United States by international passenger traffic ) ; San Diego International Airport the busiest single runway airport in the world ; Van Nuys Airport , the world ' s busiest general aviation airport ; major commercial airports at Orange County , Ontario , Burbank and Long Beach ; and numerous smaller commercial and general aviation airports . Southern California is also home to the Port of Los Angeles , the United States ' busiest commercial port , the adjacent Port of Long Beach , the United States ' second busiest container port , and the Port of San Diego . Also of note in the region is the freeway system , which is the world ' s busiest . Six of the seven lines of the commuter rail system , Metrolink , run out of Downtown Los Angeles , connecting Los Angeles , Ventura , San Bernardino , Riverside , Orange , and San Diego counties with the other line connecting San Bernardino , Riverside , and Orange counties directly . The Tech Coast is a moniker that has gained use as a descriptor for the region ' s diversified technology and industrial base as well as its multitude of prestigious and world - renowned research universities and other public and private institutions . Amongst these include 5 University of California campuses ( Irvine , Los Angeles , Riverside , Santa Barbara , and San Diego ) ; 12 California State University campuses ( Bakersfield , Channel Islands , Dominguez Hills , Fullerton , Los Angeles , Long Beach , Northridge , Pomona , San Bernardino , San Diego , San Marcos , and San Luis Obispo ) ; as well as private institutions such as the California Institute of Technology , Chapman University , Claremont Consortium of Colleges , Loma Linda University , Loyola Marymount University , Occidental College , Pepperdine University , University of San Diego , and the University of Southern California . Southern California is also the entertainment ( motion picture , television , and recorded music ) capital of the world and is home to Hollywood , a district in Los Angeles and a name associated with the motion picture industry . Headquartered in southern California are The Walt Disney Company ( which also owns ABC ) , Sony Pictures , Universal , MGM , Paramount Pictures , 20th Century Fox , and Warner Brothers . Besides the entertainment industry , southern California is also home to a large home grown surf and skateboard culture . Companies such as Volcom , Quiksilver , O ' Neill clothing division , No Fear , Sector 9 , RVCA , Body Glove and Surfline are all headquartered in southern California . Professional skateboarder Tony Hawk , professional surfers Rob Machado , Tim Curran , Bobby Martinez , Pat O ' Connell , Dane Reynolds , and Chris Ward , and professional snowboarder Shaun White live in southern California . Some of the world ' s legendary surf spots are in southern California as well , including Trestles , Rincon , The Wedge , Huntington Beach , and Malibu , and it is second only to the island of Oahu in terms of famous surf breaks . Some of the world ' s biggest extreme sports events including the X Games , Boost Mobile Pro , and the U . S . Open of Surfing are all in southern California . Southern California is also important to the world of yachting . The annual Transpacific Yacht Race , or " Transpac " , from Los Angeles to Hawaii , is one of yachting ' s premier events . The San Diego Yacht Club held the America ' s Cup , the most prestigious prize in yachting , from 1988 to 1995 and hosted three America ' s Cup races during that time . Southern California is home to many sports franchises and sports networks such as Fox Sports Net . Professional teams that are located in the region include the Los Angeles Lakers , Los Angeles Clippers , Los Angeles Dodgers , Los Angeles Angels of Anaheim , San Diego Padres , Los Angeles Kings , Anaheim Ducks , Los Angeles Galaxy , Chivas USA , and San Diego Chargers . Southern California also is home to a number of popular NCAA sports programs , such as the UCLA Bruins , the USC Trojans , and the San Diego State Aztecs . Southern California is culturally diverse , and well known worldwide . Many tourists frequent South Coast for its popular beaches , and the eastern desert for its dramatic open spaces . Northern boundary of southern California . " Southern California " is not a formal geographic designation and definitions of what constitutes southern California vary . Geographically , California ' s north - south midway point lies at exactly 37° 9 ' 58 . 23 " latitude , around 11 miles south of San Jose ; however this does not coincide with popular use of the term . When the state is divided into two areas ( northern and southern California ) the term " southern California " usually refers to the ten southern - most counties of the state . This definition coincides neatly with the county lines at 35° 47 ′ 28 ″ north latitude , which form the northern borders of San Luis Obispo , Kern , and San Bernardino counties . Another definition for southern California uses Point Conception and the Tehachapi Mountains as the northern boundary . Though there is no official definition for the northern boundary of southern California , such a division has existed from the time when Mexico ruled California and political disputes raged between the Californios of Monterey in the upper part and Los Angeles and the lower part of Alta California . Following the acquisition of California by the United States , the division continued as part of the attempt by several pro - slavery politicians to arrange the division of Alta California at 36 degrees , 30 minutes , the line of the Missouri Compromise . Instead , the passing of the Compromise of 1850 enabled California to be admitted to the Union as a free state , preventing southern California from becoming its own separate slave state . Subsequently , Californios ( dissatisfied with inequitable taxes and land laws ) and pro - slavery Southerners in the lightly populated " Cow Counties " of southern California attempted three times in the 1850s to achieve a separate statehood or territorial status separate from Northern California . The last attempt , the " Pico Act " of 1859 , was passed by the California State Legislature , and signed by the State governor John B . Weller . It was approved overwhelmingly by nearly 75 % of voters in the proposed " Territory of Colorado " . This territory was to include all the counties up to the then much larger Tulare County ( that included what is now Kings County and most of Kern , and part of Inyo Counties ) and San Luis Obispo County . The proposal was sent to Washington , D . C . with a strong advocate in Senator Milton Latham . However the secession crisis following the election of Abraham Lincoln in 1860 led to the proposal never coming to a vote . In 1900 , the " Los Angeles Times " defined southern California as including " the seven counties of Los Angeles , San Bernardino , Orange , Riverside , San Diego , Ventura and Santa Barbara . " In 1999 , the " Times " added a newer county — Imperial — to that list . The state is most commonly divided and promoted by its regional tourism groups as consisting of northern , central , and southern California regions . The two AAA Auto Clubs of the state , the California State Automobile Association and the Automobile Club of Southern California , choose to simplify matters by dividing the state along the lines where their jurisdictions for membership apply , as either northern or southern California , in contrast to the three - region point of view . Another influence is the geographical phrase " South of the Tehachapis " , which would split the southern region off at the crest of that transverse range , but in that definition , the desert portions of north Los Angeles County and eastern Kern and San Bernardino Counties would be included in the southern California region , due to their remoteness from the central valley , and interior desert landscape . Urban landscape . Southern California consists of a heavily developed urban environment , home to some of the largest urban areas in the state , along with vast areas that have been left undeveloped . It is the second - largest urbanized region in the United States , second only to the Washington / Philadelphia / New York / Boston Northeastern Megalopolis . Whereas these cities are dense , with major downtown populations and significant rail and transit systems , much of southern California is famous for its large , spread - out , suburban communities and use of automobiles and highways . The dominant areas are Los Angeles , Orange County , San Diego , and Riverside - San Bernardino , each of which is the center of its respective metropolitan area , composed of numerous smaller cities and communities . The urban area is also host to an international metropolitan region in the form of San Diego – Tijuana , created by the urban area spilling over into Baja California . Traveling south on Interstate 5 , the main gap to continued urbanization is Camp Pendleton . The communities along Interstate 15 and Interstate 215 are so inter - related that Temecula and Murrieta have as much connection with San Diego metropolitan area as they do with the Inland Empire . To the east , the United States Census Bureau considers the San Bernardino and Riverside County areas , Riverside - San Bernardino area as a separate metropolitan area from Los Angeles County . While many commute to L . A . and Orange Counties , there are some differences in development , as most of San Bernardino and Riverside Counties ( the non - desert portions ) were developed in the 1980s and 1990s . Newly developed exurbs formed in the Antelope Valley north of Los Angeles , the Victor Valley and the Coachella Valley with the Imperial Valley . Also population growth was high in the Bakersfield - Kern County , Santa Maria and San Luis Obispo areas . Natural landscape . Southern California consists of one of the more varied collections of geologic , topographic , and natural ecosystem landscapes in a diversity outnumbering other major regions in the state and country . The region spans from Pacific Ocean islands , shoreline s , beaches , and coastal plain s , through the Transverse and Peninsular Ranges with their peaks , into the large and small interior valleys , to the vast deserts of California . Geography . Southern California is also divided into : Geology . Earthquakes . Each year , the southern California area has about 10 , 000 earthquakes . Nearly all of them are so small that they are not felt . Only several hundred are greater than magnitude 3 . 0 , and only about 15 – 20 are greater than magnitude 4 . 0 . In 2012 an earthquake occurred on August 26 , 2012 , which was a swarm of over 200 events , two which had magnitudes of 5 . 3 and 5 . 5 . The San Andreas Fault puts the area at high risk , which can produce a magnitude 8 . 0 + earthquake . Regions . Divisions . Southern California is divided culturally , politically , and economically into distinctive regions , each containing its own culture and atmosphere anchored usually by a city with both national and sometimes global recognition which are often the hub of economic activity for its respective region and being home to many tourist destinations . Each region is further divided into many culturally distinct areas , but as a whole combine to create the southern California atmosphere . " * Part of multiple regions " Populace . As of the 2010 United States Census , southern California has a population of 22 , 680 , 010 . Despite a reputation for high growth rates , southern California ' s rate grew less than the state average of 10 . 0 % in the 2000s as California ' s growth became concentrated in the northern part of the state due to a stronger , tech - oriented economy in the Bay Area and an emerging Greater Sacramento region . Southern California consists of one Combined Statistical Area , eight Metropolitan Statistical Area s , one international metropolitan area and multiple metropolitan divisions . The region is home to two extended metropolitan areas that exceed five million in population . These are the Greater Los Angeles Area at 17 , 786 , 419 , and San Diego – Tijuana at 5 , 105 , 768 . Of these metropolitan areas , the Los Angeles - Long Beach - Santa Ana metropolitan area , Riverside - San Bernardino - Ontario metropolitan area , and Oxnard - Thousand Oaks - Ventura metropolitan area comprise Greater Los Angeles ; while the El Centro metropolitan area and San Diego - Carlsbad - San Marcos metropolitan area comprise the Southern Border Region . North of Greater Los Angeles are the Santa Barbara , San Luis Obispo , and Bakersfield metropolitan areas . Cities . Los Angeles ( at 3 . 7 million people ) and San Diego ( at 1 . 3 million people ) are the two largest cities in Southern California as well as all of California . In Southern California there are also twelve cities over the 200 thousand marker , and 34 cities over one hundred thousand in population . Many of Southern California ' s most developed cities lie along the coast . Housing in coastal areas can sometimes reach over a million dollars . Economy . Industries . Southern California ' s economy is diverse and one of the largest in the United States . It is dominated and heavily dependent upon abundance of petroleum , as opposed to other regions where automobiles not nearly as dominant , the vast majority of transport runs on this fuel . Southern California is famous for tourism and " Hollywood " ( film , television and music ) . Other industries include software , automotive , ports , finance , tourism , biomedical , and regional logistics . The region was a leader in the housing bubble 2001 - 2007 , and has been heavily impacted by the housing crash . Since the 1920s , motion pictures , petroleum and aircraft manufacturing have been major industries . In one of the richest agricultural regions in the U . S . , cattle and citrus were major industries until farmlands was turned into suburbs . Although military spending cutbacks have had an impact , aerospace continues to be a major factor . Major central business districts . Southern California is home to many major business districts . Central business districts ( CBD ) include Downtown Los Angeles , Downtown San Diego , Downtown San Bernardino , South Coast Metro and Downtown Riverside . Within the Los Angeles Area are the major business districts of Downtown Burbank , Downtown Santa Monica , Downtown Glendale and Downtown Long Beach . Los Angeles itself has many business districts including the Downtown Los Angeles central business district as well as those lining the Wilshire Boulevard Miracle Mile including Century City , Westwood and Warner Center in the San Fernando Valley . Orange County is a rapidly developing business center that includes Downtown Santa Ana , the South Coast Metro and Newport Center districts ; as well as the Irvine business centers of The Irvine Spectrum , West Irvine , and international corporations headquartered at the University of California , Irvine . West Irvine includes the Irvine Tech Center and Jamboree Business Parks . Downtown San Diego is the central business district of San Diego , though the city is filled with business districts . These include Carmel Valley , Del Mar Heights , Mission Valley , Rancho Bernardo , Sorrento Mesa , and University City . Most of these districts are located in Northern San Diego and some within North County regions . The Riverside - San Bernardino area maintains the business districts of Downtown Riverside and Downtown San Bernardino . Theme parks and waterparks . Los Angeles Orange County Riverside & San Bernardino San Diego Transportation . Airports . The following airports currently have regularly scheduled commercial service :