A longer list of free open Geodata sources: Get.Theinfo Google Groups

When infochimps launches finding this stuff’ll be easy. /selfpimp

- Post codes are always made up of 4 digits, an optional space, and 2 letters.
- You can therefore strip out the space and the post code will be quite alright.
- There’s never a leading zero
- The four numbers give you the city and neighbourhood, sometimes the street (depends on how big the city and how long the street is
- The letters give you the final bit about the street, what range the house number is in, and whether it’s even or odd.

Getting the official list (in all kinds of formats) costs you thousands of euros if you go to TPG (the postal service in the Netherlands). There’s also a site that tries to build a free, open catalog (Dutch site). So far they’re close to being 72% complete.

Interesting project!

If you need geocoding information by postcode (as it appears you do):
http://www.phpandmore.org/2008/06/24/australian-post-code-geo-database/

The latter would be very easy to visualise through Google Maps, since you wouldn’t need any geocoding, just marker placement.

$line = sprintf("%05d", $line);

You’re probably right about US zip codes– I’ll go back into the original CSV export to see what’s there. I did my sorting in Excel, which is annoyingly aggressive about converting text numerics to numbers, complete with leading-zero stripping, so it’s easily possible that’s what happened.

Interesting that you found a batch geocoder that seems to be single-submit under the hood. I’m beginning to think that single-submit is the only option, and I’ll just have to test with a reduced dataset until I work out a program that can do the whole conversion for me.

scragar, thanks for the pointers. I may pull some of those but will probably leave most or all of them since they’re good examples of invalid data, and any translator from postcode to region will need to be able to handle invalid data.

Jon, that sort of data would indeed be quite interesting, but we have to be very careful about how much data we associate with these postcodes. It’s probably no big deal if you’re one of a thousand people in NYC, but it could be a big deal if you’re the only respondent from Rhyl or Ottawa or Des Moines or wherever. I hope to gain enough experience that I can create those kinds of maps (or the data needed to create said maps) without being too privacy-insensitive.

1) Plymouth is in Devon and not Cornwall. Thus Devon is underrepresented and Cornwall over-represented in his data.

2) This one is more of nitpick but may be important to anyone using the data. The TS postcodes are incorrectly labelled as Cleveland, Teesside which no longer existed as of 1996. TS no refers to the Tees Valley region with postcodes North of the River Tees being in County Durham and those South of the river being in North Yorkshire.

I think what would be a really interesting mapping is correlate location against earnings and also location against the data on how respondents felt about the business and the economy (the questions on job security and whether business was growing or declining).

Given these constraints, I might suggest a hybrid approach to the mapping: One thing we can definitely get is the US data, with state only if necessary, but also with geospatial coordinates if we use the 1999 data that Sam referred to. That accounts for over half of the records. We can also get that type of data for other countries (UK, Canada, Australia) that account for most of the responses. If we use local data for these, and then supplement with requested data from Yahoo or Google for the other countries, we should be able to get a pretty complete set of coordinates. Also, for our http lookups, if we send requests for only the unique records that we have (eliminating all duplicates) that should further reduce the number of requests we have to make.

Postcode file (UK only) with region and city listed

This list includes the regions as well as the cities where that postal district is based.

If you’re just looking to get the zip codes linked with a state, I did that with a PHP function in TextMate. That accounts for over half of the records in the file:

Here’s the document:Zip code file (U.S. only) with states listed
and the code: TextMate custom command

Eric – I think that somewhere along the line a lot of these US zip codes got their leading zeros stripped out. I added them back in for this file.

It looks to me like it will take some attention to each specific country to get the geographic breakdowns for the different postal codes. I’ve gathered postal data on about half of the countries, but it seems to me that getting specific geographic data on a lot of countries will be a lot of work with very little return (i.e. I’m not sure it will make much difference to users whether we break France down into its 100+ geographical regions or not). It might be most useful to break down the largest geographic areas (Canada, Australia, Russia, etc.) and just list the others as countries.

Anyway, here’s the U.S. portion of the file. I’ll see if I have time to do other countries and post them here as well.