The City of Angels, as it is known, is a global city, and the Los Angeles Combined Statistical Area (CSA) is the third largest in the world, after Greater Tokyo and New York. It's also the 66th most populous city proper in the world, and the metropolitan area is the 18th largest. The greater Los Angeles area is much larger, though, and its metropolitan area has a population of 12.8 million, with 18.5 million living in the CSA. The Greater Los Angeles Area, also referred to as Southland, refers to both the urbanized area and the Combined Statistical Area.
http://worldpopulationreview.com/us-cities/los-angeles-population/
The general concept of these areas is one of a large population nucleus, together with adjacent communities that have a high degree of economic and social integration with that nucleus. Using the data from the 2000 census, the OMB revised or created new Metropolitan Statistical Areas (MSA) across the country. These new Metropolitan Areas become the standard geographic areas for which economic data are produced by cooperative programs of the Bureau of Labor Statistics.
http://www.labormarketinfo.edd.ca.gov/LMID/Metropolitan_Areas_in_CA.html
Los Angeles Population Density. Based on the 2010 census data, Los Angeles had a density of 7,544.6 people per square mile (2,910/square kilometer). While it's the second-most populous urban area, Los Angeles is the single most densely populated area in the United States.
http://worldpopulationreview.com/us-cities/los-angeles-population/
According to the 2010 Census, the Los Angeles metropolitan area had a population of more than 12.8 million residents, while the larger metropolitan region had an estimated population of 18.1 million.
http://worldpopulationreview.com/us-cities/los-angeles-population/
The Los Angeles Regional Office is responsible for all data collection, data dissemination, and geographic operations under a new service area boundary. The Seattle Regional Office closed in late 2012 and transferred all responsibilities to the Los Angeles Region. In addition, the Denver Region transferred its responsibility for Nevada. States within the Los Angeles Region's service area include Alaska, California, Hawaii, Idaho, Nevada, Oregon and Washington. The new boundary is part of the Field Realignment as shown on this Map of New Regional Office Structure [PDF 632k].
http://www.census.gov/regions/los_angeles/
Combined Statistical Areas (CSA) - adjacent Metropolitan and Micropolitan Statistical Areas, in various combinations, may become the components of a new set of areas called Combined Statistical Areas, if specified criteria are met. The EDD produces data for the MSA components of the CSA, not the CSA itself.
http://www.labormarketinfo.edd.ca.gov/LMID/Metropolitan_Areas_in_CA.html
Micropolitan Statistical Areas – a new set of statistical areas - have at least one urban cluster of at least 10,000 but less than 50,000 population, plus adjacent territory that has a high degree of social and economic integration with the core as measured by commuting ties.
http://www.labormarketinfo.edd.ca.gov/LMID/Metropolitan_Areas_in_CA.html
In California, there are four Metropolitan Divisions that combine into two MSA, one in Southern California and the other in the Bay Area. The EDD will publish data at the Metropolitan Division level to maintain the same geographic configuration for these two MSA that is currently published.
http://www.labormarketinfo.edd.ca.gov/LMID/Metropolitan_Areas_in_CA.html
According to the UN, Tokyo is the world’s most populous metropolitan area with an estimated 37.8 million people in 2014. The next closest is the Seoul National Capital Area with a population of 25.6 million people or over 10 million fewer than Tokyo!
http://brilliantmaps.com/tokyo-vs-us-cities/
Still, its crazy to think that the same number of people live in Greater Tokyo as live within the city boundaries of the following US cities ranked by population: 1  New York – 8,491,079. 2  Los Angeles – 3,928,864.  Chicago – 2,695,598.
http://brilliantmaps.com/tokyo-vs-us-cities/
population greater los angeles metro area
The population of Greater Los Angeles Metro Area is 12.8 million. Los Angeles Metropolitan Statistical Area had a population of 12.8 million, with 18.5 million living in the CSA.