[OSM-talk] Most complete cities and administrative divisions database

[M∡rtin Koppenhoefer]

2011/1/26 Sami Dalouche <skoobi at free.fr>:

he geonames project (http://www.geonames.org/) provides over 7 million
POI, and 2 million of them are cities.


2 million can IMHO only refer to all settlements, not just to cities.
There is around 7 billion people living on earth, ~ half of them in
cities. If you divide 3,5 billion people by 2 million, you get an
average of 1750 people per city. Not quite much ;-) (or they have lots
of multiple entries).

> So, more specifically, here are my questions :
> 1/ how many cities are present in OSM ?


this is easy to answer:
http://taginfo.openstreetmap.de/keys/place#values
492 155 village
397 919 hamlet
57 083 town
44 450 suburb
18 942 city

> 2/ how many of these cities are also associated to polygons that delimit
> them ?


are you asking about the city or about it's administrative boundary?
http://taginfo.openstreetmap.de/keys/boundary#values


> 3/ Are countries and administrative divisions also explicited in OSM ? (e.g.
> USA, California, Orange county, ..)


you can do this with relations


> 4/ Are there polygons for these administrative divisions and countries ?


you can get them from the relations (if the relations are there and
are clean). Have a look at type=boundary and type=multipolygon

Cheers,
Martin