Postcodes / Zipcodes 90% open

What data is expected?

A database of postcodes/zipcodes and the corresponding geospatial locations in terms of a latitude and a longitude (or similar co-ordinates in an openly published national co-ordinate system). A database which gives a location in terms of the name of a town or a street without lat/long co-ordinates is not considered acceptable unless the name of the town or street can be further converted to a latitude and longitude by means of other open data (eg an open gazetteer with latitude and longitude attributes).

What data is available

•   Does the data exist? Yes
•   Is data in digital form? Yes
•   Publicly available? Yes(as Zip-Code Tabulation Areas (ZCTA) published by US Census Bureau)
•   Is the data available for free? Yes
•   Is the data available online? Yes (Here)
•   Is the data machine readable? Yes (TSV, SHP)
•   Available in bulk? Yes
•   Openly licensed? Yes(Here)
•   Is the data provided on a timely and up to date basis? No

Details

This dataset in the US presents some challenges as there is a mixture of data available.

The US Census provide zip-code centroids as part of their 2010 Gazetteer located at http://www.census.gov/geo/maps-data/data/gazetteer2010.html in the form of the Zip-Code Tabulation Areas:

http://www.census.gov/geo/maps-data/data/docs/gazetteer/Gaz_zcta_national.zip

This data is open data (openly licensed, and machine readable etc).

However, there are some limitations of this data as it is based off the census, the last of which was in 2010. Thus, over time this database gets out of date versus the authoritative data held by the USPS. Given this, the data is marked as not timely.

In addition, the ZCTA isn’t as complete as the USPS zip-code list as it focused on geographical areas and so its coverage of e.g. PO boxes is more limited. However, given the specifications of this dataset this should not be considered a major limitation and so we have not docked points anywhere else.

More on Zip-Codes and the USPS

The full database of zip codes from the USPS has not yet been found although it looks like products are available for sale, and they are multiple datasets that can help to provide a whole picture.

The ZCTA file produced by the US Census Bureau is useful but is not the full USPS Database of Zip Codes and lookup tables. Instead, this is a census related product produced every 10 years.

"You may have noticed that Census Bureau products refer to “ZIP Code tabulation areas (ZCTAs)” and not simply to ZIP Codes™. The reason that we cannot tabulate data for ZIP Codes is that they do not have distinct geographic boundaries. Designed by the U.S. Postal Service for use in mail delivery, ZIP Codes represent carrier routes made up of individual addresses. A true representation of ZIP Codes would separate out individual housing units and releasing data for them would risk disclosing personally identifiable information". https://ask.census.gov/faq.php?id=5000&faqId=10488

The ZCTAs are not the same as the (regularly updated) USPS postal code lookup files or the postal code database with addresses and Lat Long. Those data are for sale and a number of USPS services are resold.

There is an USPS API for companies to integrate their their systems - https://www.usps.com/business/web-tools-apis/address-information-api.htm Some date exchange for companies - https://www.usps.com/postalone/program.htm Segmentation direct mail tools https://www.usps.com/business/pdf/Segmentation_WP.pdf Lots of info about databases and services - https://about.usps.com/publications/pub32/pub32_terms.htm and lots of private sector tools such as http://www.zip-codes.com/zip-code-database.asp?gclid=CLG5_NWPncICFWSK2wodgIQAnA

In addition, there are also some crosswalk files made by HUDs and posted on data.gov http://catalog.data.gov/dataset/hud-usps-zip-code-crosswalk-files