Zip Code / ZCTA Boundary Encoded Dataset
ZCTA "zip code tabulation area" boundary data is available free from the US Census Bureau. Generally, each ZCTA corresponds to a single zip code. Sometimes one zip code contains two or more ZCTAs and vice-versa. Certain zip codes, for instance those that are exclusive to post office boxes, do not have a corresponding ZCTA.
Still, in many cases, the ZCTA dataset is close enough to satisfy site requirements for displaying zip code boundaries. It certainly provides an economical way to bridge the gap until a more expensive solution is warranted.
The US Census Bureau provides ZCTA boundary data in raw form as a free download. Austin Rail Yard has converted this raw data into the Encoded Polyline Algorithm Format for use with Google Maps. We use this dataset internally where appropriate. We also offer this encoded dataset, along with a small example Rails app, for $199.
For purchase information, please click here.
Please visit acts_as_architect for further discussion of Rails-based solutions that use this and other encoded datasets.