The World's Most Populous Cities

I said earlier in the week that I would attempt to compile a list of the world's largest cities. However, this in itself is easier said than done. There are many different measures of what a city is, but there are 3 main categories -

1) City proper
- This is the most straightforward definition of a city. It is a measure of how many people live within a community's politically defined boundaries. So if we take London as an example, this would be all the people living in the 33 districts from Hillingdon (West) to Havering (East), and Enfield (North) to Croydon (South). This equates to roughly 8.4 million people, and these are in the area covered by the Metropolitan Police and are able to vote for the Mayor.

2) Urban Area
- This is probably what most people think of when they imagine a city. Put simply, this is essentially the measure of continuous sprawl without too much green space in between. If we take the case of London again, this would include most of the 33 districts, plus certain parts of the Home Counties. These are generally right on the border, and include Watford, St Albans, Hemel Hempstead (Hertfordshire), Bracknell (Berkshire), Woking, Guildford (Surrey), north west Kent and Harlow (Essex), making up about 9.8 million people. This is most likely to be the criteria used for comparisons of international cities and I will do a guide to these over the coming days.

3) Metropolitan Area
- This is difficult to define, especially when comparing internationally. Generally, it refers to the amount of people within a practical commutable distance from a city. In the case of London this refers to the majority of the Home Counties, with a bit of wiggle room here and there. This means that it can (by certain definitions) include places like Southend, Milton Keynes, Reading, Luton and Dover, which are obviously distinct from London and where nobody who came from there would consider themselves a Londoner (It stretches over more than 15 million people). This definition is probably best used as an economic measure.

As you can see from these figures, the definitions often produce wildly different outcomes...

(Numbers) represent millions of people.

   City proper                                  Urban Area                          
1) Shanghai (24)                            1) Tokyo (38)
2) Beijing (21)                               2) New Delhi (25)
3) Karachi (21)                              3) Shanghai (23)
4) Lagos (17)                                 4=) Mumbai (21)
5) Istanbul (14)                              4=) Sao Paulo (21)
6) Guangzhou (13)                        4=) Mexico City (21)
7) Mumbai (12.5)                          7) Osaka (20)
8) Moscow (12)                             8) Beijing (20)
9) Sao Paulo (12)                           9=) New York (18.5)
10) Lahore (11.5)                           9=) Cairo (18.5)

Hopefully once I've had a better look at this I can do a proper rundown of the largest urban areas for future reference. This sort of thing is unfortunately a quizzer's nightmare as all the information is so at odds with other available information. I'll just have to see how much of a nightmare this turns into.