Economics should be open

February 8, 2010

Fun with GIS, California zip9, cbg, latlon

Filed under: Uncategorized — howardchong @ 5:14 am

So, I’m having lots of “fun” with GIS right now.

I’m having to map zip9 (AKA zip+4, zip 9, zip5+4) in California to census block groups (and census tracts) (CBG / CT) and then to latitude and longitude.

I’m having to do this because I haven’t found a similar list online. There are some data vendors, but I’m old-fashioned and like to see the original data sets and do the merge myself.

Odd thing, though, is that I can’t find any zip9 polygons. I just have them as points. Which somewhat makes sense since zip9s are usually a couple of blocks at most, but it’d be nice to know which zip9’s are very large in area and which are small. (Could I back this out by checking the nearest neighbor distance?)

This is a pretty large spatial join since I have a count of 2,854,068 zip9’s in California and something on the order of  10,000-100,000  CBGs.

If you need crosswalks / correspondence tables for this data, please feel free to ask. Preference given to academic researchers and I will ask for a nominal fee (<$50) for time spent preparing it for you, especially if you are not in academia/public-sector.


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