There are 13 multi-state US Census' ZIP Code Tabulation Areas (ZCTAs): 02861, 42223, 59221, 63673, 71749, 73949, 81137, 84536, 86044, 86515, 88063, 89439 & 97635.
As others have mentioned, there are a few different ways to figure out the area covered by a ZIP Code, but ZCTAs are the easiest, and the only official version that I know of.
So your ...
There really isn't a way to tell this; since there is not a ZipCode boundary shape that is defined by the USPS. ZipCodes are defined by a bounding box of Streets delivered to by carriers from a particular distribution center. So you would need to take the USPS AIS data and extract by ZipCodes the streets that are delivered by a given Post Office, then Join ...
UPDATE: 2016 FSA Census Boundary files are now available (as of Sept 13, 2017 according to their site).
Stats Canada has since released the Forward Sortation Areas Boundary files (as of February 5, 2013 according to their site).
Download Page for all 2011 Census Boundary Files
Download Page for all 2016 Census Boundary Files
Statistics Canada has ...
The US Census Bureau derives approximate boundaries for ZIP codes based on the addresses contained within them, called ZIP Code Tabulation Areas (ZCTAs).
They publish relationship files that describe how their ZCTAs map to various other geographies. If you examine the ZCTA to Place relationship file you can see how they map to cities and towns. You can ...
One of the biggest misconceptions GIS users have about ZIP codes is that they are a set of polygons that cover the United States--they are not. ZIP codes are a system used by the Postal Service for sorting mail before delivery, and nothing more. If an address receives enough mail, the USPS will just assign them a ZIP code to improve sorting efficiency. Many ...
We've recently released reconstructed postcode boundaries in shapefile format for UK postcode areas, districts and sectors (reconstructed from unit postcode geocodes using Voronoi etc). They are free to use. Obviously the reconstruction is approximate and may not be suitable for all purposes. They are available at http://www.opendoorlogistics.com/data.
You can download Code-point Open from https://www.ordnancesurvey.co.uk/business-and-government/products/code-point-open.html to get a coordinate of each postcode unit that you can join to your existing postcodes.
Someone has done it using various royalty and copyright free sources of data - see http://random.dev.openstreetmap.org/postcodes/. In my view the best is the Code-Point Opendata as it comes straight from Royal Mail. I don't think it's quite the same as the actual Royal Mail files but it's probably accurate enough. The files don't seem to be available so you ...
All of the world's postal code formats are tabulated here: http://www.grcdi.nl/gsb/world%20postal%20code%20formats.html
Some countries may precede their postal codes with a country code, as you describe in your question; and where codes contain spaces or punctuation they may be found written without, but even then there are only a few hundred possible ...
Ordnance Survey provides some free open data on postcodes called 'Code-Point Open'. It is a csv of the post-code with a lat long attribute. I'd suggest getting hold of this data then extracting just the post-codes you're interested in.
Information on the layer can be found here, and can be downloaded from here. Just need to fill in a form and they send ...
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.
You can download the 5 ...
2016 TIGER Data with PostGIS
As a special caveat, ZCTA data isn't USPS Zip Codes. It's an approximation of it. USPS Zip Codes are really horrible and not useful except to approximate. Everyone, including every governmental entity other than USPS, and (the Census for making ZCTA) ignores them entirely. If USPS wanted to a grow up a bit, they'd just convert ...
EZ-Locate (TeleAtlas - owned by TomTom)
NAVmart (NavTeq owned by Nokia)
Via Michelin (API and better coverage in Europe rather than globally)
Geonames (good open-source - patchy ...
You need census data, the spatial files for postal code geography (census tacts, dissemination areas ..... some form of spatial parameter) and you should read up on the Cluster Analysis Tool in ArcGIS. The database containing the the census data includes household income, family size, etc, etc (most of the data you will need). The cluster analysis will ...
We've recently released free UK postcode boundaries in shapefile format for UK postcode areas, districts and sectors (reconstructed from unit postcode geocodes using Voronoi etc). They are free to use. Obviously the reconstruction is approximate. They are available at http://www.opendoorlogistics.com/data.
This is probabaly not the answer you are looking for, but here it is:
You won't find them, since no one (not even the Postal Department) has Authentic Boundaries.
Pin codes in India are a way of indexing Post Offices. Multiple Post Offices can have one pin code, and one Post Office can deliver to Multiple Pincodes.
It's a Myth that there is such a thing ...
I am sorry I dont know of any specific algorithm, but I could find some links which might be helpful.
Purchasing Power in Europe
A New Method for Classifying Customer Purchasing Power
Truncated ARMA-GARCH Model and MCMC Algorithms
Hope it helps...
If you qualify for the OS PSMA (Public Sector Mapping Agreement) then you can get Codepoint with polygons for free. They provide an excellent service and it's delivered the very next day.
Have a google for PSMA to see if you qualify.
Try using Bing Geocoder, I believe they do UK, so you should be able to look up the coordinates of the zip code and in the results you will see the cities that correspond globally to that zip code...
P.S., Don't use google geocoder for UK, it doesn't work properly from personal experience.
Before going to WMS I would ask yourself why you need to load all 20,000 points.
Are your users able to meaningfully visualize that many points? Would you be better served displaying density of points until a specified zoom has been achieved?
After that - the other answers are your best bet. Use a WMS for that much data.
Edit for comment
You could ...
This is easy to remedy using Python. If you are in ArcGIS, you can simply use Python in a field calculator to strip the space from the field.
The code would look something like:
which will remove the space in the postal code field. You can also do this in raw Python, but you would have to read in your csv file, make the change, ...
You can create your own from:
Supply format: CSV
Code-Point Open provides a precise geographic location for each
postcode unit in Great Britain. The product is a CSV file containing
postcodes, grid references, NHS® health and regional health authority
UK postcodes don't cover polygons. They cover a set of individual delivery points which are not necessarily contiguous.
It is certainly possible, given the co-ordinates for these delivery points, to describe a polygon such that all the co-ordinates are within that polygon. However, such a polygon would not be a unique solution - there would be many polygons ...
Ordnance Survey Open Names (open data) gives you postcode and populated place, where populated place is a city, town, village, or some other place where people live.
SW1A 1AA -> City of Westminster
RG4 7LR -> Caversham
OX1 1AA -> Oxford
Mapsdata and other similar services allow you to load up Postcode and attribute data in .xls or .csv format for free and then view it on a map if that's the end product that you're looking for.
Here's a wiki description of how the postal code system works using the first or first and secondary alpha characters. It's regional specific and not city, ie PH ...
Thanks to Aragon but I found a simpler solution. I ended up using the dissolve function in QGIS. I didn't realise it was possible to do this based on a grouping value. It took a long time to process but got the job done with minimal effort. Definitely a case where learning the correct terminology probably would have gotten me to the answer faster.
As a side ...