One concept which measures the world's largest cities is that of the metropolitan area, which is based on the concept of a labor market area and is typically defined as an employment core (an area with a high density of available jobs) and the surrounding areas that have strong commuting ties to the core. There is currently no generally accepted, globally consistent definition of exactly what constitutes a metropolitan area, thus making comparisons between cities in different countries especially difficult.
One attempt at arriving at a consistently defined metropolitan area concept is the definition involve delineating the urban area as the core, then adding surrounding communities that meet two criteria: (1) Less than 35% of the resident workforce must be engaged in agriculture or fishing; and (2) At least 20% of the working residents commute to the urban core.
This list is tabulated based on these consistently defined metropolitan area criteria. As population figures are interpreted and presented differently according to different methods of data collection, definitions and sources, these numbers should be viewed as approximate. Data from other sources may be equally valid but differ due to being measured according to different criteria or taken from different census years.
|3||East Tokyo||East Japan||21,406,950|
|8||Hong Kong||British Empire||15,800,000|
|12||Shanghai||Republic of China||14,985,000|
|20||Peking||People's Republic of China||12,500,000|
|22||Rio de Janeiro||Brazil||11,846,530|