Search results
Results from the WOW.Com Content Network
ZIP codes represent groups of addresses or delivery routes. The +4 codes might narrow it down to a block, a building or single organization. ZIP+4 data is available directly from the USPS (including a file that relates it TIGER) or from third parties who have taken the USPS data and repackaged presumably with value added.
The U.S. Department of Housing and Development provides a crosswalk between standard 5-digit ZIP codes and census tracts. This is a hard problem, as neither set's units are contained in the others'. (And units needs not be polygons on a map either.)
Some background: The USPS maintains zip codes as sets of delivery zones(5 digit) and routes(+4 digits), usually along streets with address boundaries. USPS does not maintain zip codes in any shape format. I had the issue of finding a viable source as well. I narrowed my possible solutions to the following 4 and chose to go with #3.
A five-digit ZIP code covers an arbitrary collection of delivery points (addresses). The USPS is the sole determiner of what ZIP code is assigned to what address, so they are the best source of current and correct data, which changes monthly. Cheap sources of current data are vendors like Semaphore Corporation.
This help content & information General Help Center experience. Search. Clear search
If an address is deliverable, a ZIP+4 is assigned as opposed to just a 5 digit ZIP. Some of the licensees of the data match the street and address range from the USPS with an external street centerline file to provide a geographic point representing a ZIP+4. This level of detail can be generalized back to the ZIP code and derive a ZIP point.
Zip Code Tabulation Areas (ZCTA) are a US Census product derived from the Zipcodes defined by the USPS which, as a federal entity, may cross state and other administrative boundaries. They are semi-fuzzy boundaries based on the logistical delivery of mail and are subject to changes between censuses.
I do have Esri Street Map Premium service and that allows for 9 digit zip to Lat/long but not Address to Zip+4. Odd. There is a "PostalExt" field in the output but i does not populate. very annoying. Reference data must be available for the boundaries (or at least centroid) for this data but it is not available for use in the street map premium ...
Because of this seeming inconsistency, a 5 digit ZIP Code is not as valuable as a 9 digit (or ZIP+4) code. The ZIP+4 code designates a specific area, typically a city block or grouping of houses and so is much more precise. There are 42k unique ZIP Codes currently in use and that means that the possible number of ZIP+4 codes is 420 Million.
Where can I get a TopoJSON file with 3 digit zip codes (zip3) shapes I have searched for days and I just can find 5 digit zip codes shapes.