The MSA is in turn made up of two 'metropolitan divisions': Office of Management and Budget as the Los Angeles–Long Beach–Anaheim, CA Metropolitan Statistical Area (MSA), with a 2021 population of 12,997,353. The Los Angeles metropolitan area is defined by the U.S. Oxnard–Thousand Oaks–Ventura, CA MSA Los Angeles metropolitan area Over time, droughts and wildfires have increased in frequency and become less seasonal and more year-round, further straining the region's water security. In 2015, the Greater Los Angeles population was estimated to be about 18.7 million, making it the second largest metropolitan region in the country, behind New York, as well as one of the largest megacities in the world. census, the smaller Los Angeles metro area had a population of nearly 13 million residents. Throughout the 20th century, Greater Los Angeles was one of the fastest-growing regions in the United States, but growth has slowed since 2000.

San Diego–Tijuana, though contiguous with Greater Los Angeles at San Clemente and Temecula, is not part of it because of the fact that it is separated from Greater Los Angeles by Camp Pendleton north of Oceanside, California located in San Diego County all the way to San Ysidro, California at the American-Mexican border, together both form part of the Southern California Megalopolis while at the southern most point is Tijuana, Mexico at the border south from San Ysidro, California. It has a total area of 4,850 square miles (12,561 km 2). The Census Bureau designates the latter as the Los Angeles–Long Beach–Anaheim metropolitan statistical area, the fourth largest metropolitan area in the western hemisphere and the second-largest metropolitan area in the United States, by population. There are four contiguous component metropolitan areas in Greater Los Angeles: the Golden Empire that makes up the city of Bakersfield within Kern County the Inland Empire, which can be broadly defined as Riverside and San Bernardino counties the Ventura/Oxnard metropolitan area (or Ventura County) and the Los Angeles metropolitan area (also known as Metropolitan Los Angeles or Metro LA) consisting of Los Angeles and Orange counties only. It is the 3rd largest metropolitan area by nominal GDP in the world with an economy exceeding $1 trillion in output (behind Tokyo and New York City). In addition to being the nexus of the global entertainment industry (films, television, and recorded music), Greater Los Angeles is also an important center of international trade, education, media, business, tourism, technology, and sports. Of this, the contiguous urban area is 2,281 square miles (5,910 km 2), the remainder mostly consisting of mountain and desert areas. Census Bureau, the Los Angeles–Anaheim–Riverside combined statistical area covers 33,954 square miles (87,940 km 2), making it the largest metropolitan region in the United States by land area. Greater Los Angeles is the second-largest metropolitan area in the United States (after New York's), with a population of 18.5 million in 2021, encompassing six counties in Southern California extending from Ventura County in the west to San Bernardino County and Riverside County in the east, with Los Angeles County in the center, Kern County in the North, and Orange County to the southeast.

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