[Note 2]

Population totals for the cities of the world must always be taken skeptically, primarily because of the many legitimate ways to draw boundaries around most cities. Official administrative jurisdictions usually provide a smaller total than "metropolitan area" counts, but the latter can be be defined in many ways. The data provided in this table come from ESRI, the world's leading Geographic Information System (GIS) software manufacturer. They appear to be based on varying "official" tabluations. The population for Los Angeles is clearly the population of the County of Los Angeles (not the City, which was about 3.5 million in 1990), nor the U.S. Census's Consolidated Metropolitan Area, which was about 15 million in 1990. New York's total is clearly the Consolidated Metropolitan Area (not Greater New York's five Boroughs). Had the same unit been applied to Los Angeles, it would have ranked sixth rather than ninth, above Mexico City, but the estimate for that megacity seems to exclude the sprawling suburbs, which pushed estimates of Mexico's capitol as high as 20 million in the early 1990s. In sum, the numbers here should be taken only as indicators of relative magnitude. I divided the total list of great world cities into two classes: those above and below 5.8 million, only because that figure delimits the 25 largest urban places in the world.