[postgis-users] extracting zipcode bundaries from tiger2005se basedata

[Stephen Woodbridge]

Dylan Beaudette wrote:
> Hi everyone,
> 
> On the GeoServer website there are excellent directions on how to extract 
> specific information from the tiger2005 base data. However there are no 
> instructions covering the extraction of zipcode boundaries. Does anyone know 
> of a good way to go about doing this in postgis ? I already have the 
> tiger2005se database setup.
> 

Dylan,

Here are a couple of possible solutions.

A. this is how the census does it

1. create all the block polygons
2. assign each block polygon a zipcode based on analysis of the zipcodes 
on the inter edge of the block polygon
3. union all the block polygons for each unique zipcode
4. look for small islands where a block is surrounded by other other 
zipcodes and deal with it.

B. probably a bad option

1. collect all edges that belong to a zipcode excluding '00000'
2. pass this to buildarea() function.
3. this will probably fail because of gaps in the edges where zipcodes 
are not assigned.

C. download the zcta polygons for Census, inspite of the fact they are 
based on Tiger2000 files.

-Steve