Rhine-Ruhr

On my lists of cities, I have included Rhine-Ruhr as a city with about 11 million people.  But there is a difference between a city and a region.  For example, in China, the cities are more like districts, and only the urbanized areas should be included, and the only real metropolitan area in China is Guangzhong-Foshan.

And even having a contiguous developed area does not mean that it part of the same city.  A metropolitan area is the core city plus the surrounding suburbs.  But there could be multiple metropolitan areas that touch.   In the US, this is the difference between a "Metropolitan Statistical Area", and a "Consolidated Statistical Area".  Different metropolitan areas have their own energy and identity.  While there is a tendency to combine them to get up higher on "the list", I think it is better to be honest and consistent about the areas.  This isn't always easy.  And that is why I have more cities on the lists to encourage listing them separately.

Ok, back to Rhine-Ruhr.  It seems like this is really made up of 6 different "Larger Urban Zones", as they are known in Europe:
Ruhr LUZ (5.2 million)
Dusseldorf LUZ (1.5 million)
Monchengladbach LUZ (260,000)
Wuppertal LUZ (351,000)
Cologne LUZ (1.9 million)
Bonn LUZ (918,000)

It is really difficult to estimate GDP, but I am using these old numbers:
Ruhr (eu 30k/person; total $203 bn)
Dusseldorf (eu  54k/person; total $105 bn)
Monchengladbach (eu 30k/person; $10 bn)
Wuppertal (eu 30k/person; total $14 bn)
Cologne (eu 39k/person; total $96 bn)
Bonn (eu 34k/person; total $41 bn)
Total for area: $469 bn.  I previously estimated the larger region at $430 bn, so this seems reasonably accurate.



So there you go.  Rhine-Ruhr should no longer be listed as a city, but Ruhr is, and still impressive.

See also: http://aftermath2022.blogspot.com/2012/03/rhine-ruhr-metro-area.html