The Bangkok Metropolitan Area covers an area of 7,761.50 km² and has a registered population of 10,100,964 (as of June 1, 2008), with a population density of 1,301.42 per km². Due to the success of the service and tourism industry in Bangkok, the city has gained in popularity not only among provincial Thais from the rural areas but in many countries in the Indochina region as well as many South Asian countries for work. In the past 20-30 years, there has been a large movement of Indians (Sikhs), Pakistanis, Persians, Burmese, Cambodians, Laotians and many others emigrating to Bangkok. The city is now home to nearly 3-4 million illegal foreigners, a third of which are not of Thai descent. There are large numbers of workers who reside outside the metropolitan area and flux into the city for day time jobs. Therefore, with regards to the population, the registered number of approximately 10 is dwarfed by the 15 million in the city during the day. However, during New Year's Break, Songkran Break and other long weekends, the capital often seems deserted of many taxi drivers, side street vendors and other unaccounted forms of informal services in which many illegal residents engage in.
Many consider Bangkok's built up area limited only within the Bangkok province, however, large communities and centers are currently cropping up throughout the metropolitan area. The rapid growth of suburban development is increasingly connecting these city centers. Much similar to Los Angeles, the city's many urban centers are now turning into cities in themselves and certain Bangkokians no longer enter the city core area due to businesses basing their headquarters at different city centers of the city. The built up area consists primarily of Bangkok province, parts of Samut Prakan province, parts of Nonthaburi province, parts of Pathum Thani province, and the border areas of Samut Sakhon and Nakhon Pathom to the Bangkok province. Samut Prakan, Nonthaburi, Pathum Thani and Samut Sakhon all have a city center and downtown core as they were once separate cities and due to the large growth of suburbs along the outskirts of Bangkok, have created an extremely large conglomeration of the urban area. Bangkok's freeways are one way for many middle class workers to commute to city centers. However, lower class workers normally work in areas of their residence unless they are employed by companies, they would use the city's extensive bus routes or carpool with tens of workers in the early hours of the morning.
Currently, the city's growth is not stricken to a certain area. The land value of the downtown core in each city is skyrocketing especially in the Bangkok downtown giving rise to a Manhattanization in city core areas. The outskirts of each city is growing and the boundaries are no longer visible between each province and city center. Due to the speed of this urban sprawl over the past twenty years, the Bangkok Metropolitan Administration has sought to tackle rising problems of commute times, pollution and deteriorating air quality. Recent administrations have been relatively successful in conserving the air quality, however the city still lacks an effective mass transit network and a clean and resolving plan on implementing environmental practices. This form of urbanization is not only limited to Bangkok but traces can be found in metropolitan areas where there has been a quick surge in population. The Pattaya-Chonburi Metropolitan Area is a prime example due to the increase in residential high rise living and the rush for commercial office space, in the Nakhon Ratchasima Metropolitan Area, Greater Hatyai-Songkhla Metropolitan Area and Chiang Mai Metropolitan Area.