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Hi,
On Tue, 25 Sep 2001, Robert Spier wrote:
>
> From: Robert Spier <rspier@pobox.com>
>
> http://newbabe.mengwong.com/~rspier/lapm/map.gif
>
> I thought it would be neat to see how we (la.pm) is distributed
> geographically around the region. I'm going to do this with a service
> called Tiger, provided by the Census Bureau.
Whoo!
> In order to do this, I need to know where everyone lives and works.
> Tiger takes Latitude and Longitude for it's coordinates, so thats what
> I'm asking you provide.
>
> How do you find out where that is?
>
> http://www.census.gov/cgi-bin/gazetteer/
> (The gazetteer will locate your zip code, which is close enough.)
Some interesting points about ZIPs[1] and TIGER[2].
Gazetteer presents lat/lon coordinates for a ZIP Code calculated as the
ZIP's center point. ZIPs can cross counties and even states so it's
possible to get a lat/lon for your ZIP that isn't even in your county.
Of course this is a good thing where you want to introduce a differential
in your map spots.
There have been lots of changes in ZIPs since 1990 so don't be surprised
if your ZIP isn't in Gazetteer. Also, ZIPs assigned to organizations or
businesses without respect to geography will not be in Gazetteer. For
example, my business ZIP is Washington DC 20233 but my physical location
is Maryland so 20233 isn't in the Gazetteer.
TIGER for Census 2000 uses the ZCTA[3] (ZIP Code Tabulation ARea) as a
replacement for ZIP codes which are not suitable for mapping as they are
not always polygons. Many ZIP code areas directly correspond to a ZCTA
but not all do.
More than you wanted to know -
-lisa
[1] ZIP Code is a registered trademark of the USPS
[2] TIGER is a registered trademark of the US Census Bureau
[3] ZCTA is a trademark of the US Census Bureau
http://ftp.census.gov/geo/ZCTA/zcta.html
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