Where in the world is metro area data?

May 21, 2007 4:21 PM

Is there a freely available database of major metro areas?

I have a bunch of locations I'd like to clump together by metro area (rather than city), but I'm not sure where to get the metro-area data. I know that geonames offers a dump of cities with a population over 15,000, but that's not quite what I'm after. If I have a point that's Sunnyvale, CA, for example, I'd like to know that's generally "Bay Area". I might be dreaming, but does a list of major metros (and their coordinates) across the world exist?

posted by pb to computers & internet (8 comments total)

I don't know about the world, but you can do this in the US with a database of place names and their geographic coordinates from the USGS and a data of MSAs or BTAs and their boundaries, depending on how granular you want to be, from the FCC.

If that's good enough for you, I could probably generate a list from my PostGIS database which already has those databases loaded into it.
posted by wierdo at 4:44 PM on May 21, 2007

In the US, that should be available from the Census website. The real problem you will face in trying to have one list for the world is that definitions of "metro area" are not standardized by country. That is, China's definition of the metro area is not the same as Mexico's is not the same as the US's is not the same as UN-HABITAT's. (This is why different lists of "biggest cities in the world" can be quite different, because they are based on radically different population estimates and area boundaries.)
posted by Forktine at 5:14 PM on May 21, 2007

The geowanking list would be a good place to ask this question.
posted by Nelson at 5:18 PM on May 21, 2007

Google has a metros list in their ad service, but no lat/lon coordinates for boundaries.
posted by mathowie at 5:24 PM on May 21, 2007

You could use something like Yahoo's Map Image API, which lets you specify the zoom parameter. In Rasmus' example, he lets you put in "Sunnyvale, CA" to get a map tile or (more relevantly) a Lat/Lon/Precision request. You could maybe pull out to a zoom level of 8 and see what the response was? Or try going back-and-forth once, get city > reduce significant digits/zoom out > requery for locale.

Kinda hacky, but at least there's an API.
posted by anildash at 9:34 PM on May 21, 2007

Here are the Census definitions for all US metros, with the counties that belong in each. From there, it's relatively straightforward to find boundary information online for the counties.
posted by waxpancake at 9:12 AM on May 22, 2007

Thanks everyone for the ideas. The county approach seems like the best bet, though that only covers the US.

I need to dig into the MSA and BTA acronyms a bit more. Maybe the answer is there, but again, sounds like that's US-only. I think Forktine nailed the reasons why this is tough.
posted by pb at 8:35 PM on May 23, 2007

This sort of analysis is easy in the US, because the Census hands you the data on a platter. What is hard is making comparisons between countries (and knowing when and when not to question the assumptions embedded within the data).

To give a sense of how this is complicated, take a look at these three links, and note how the rankings of municipal areas vary:

Wikipedia

Citypopulation.de

Article (pdf)
posted by Forktine at 11:07 PM on May 23, 2007