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NOTE: This began as a question on Stack Overflow, which has subsequently been closed. I also noticed a similar question about Most Up-To-Date Source for US Zip Code Boundaries, but I believe this question is different in that I'm not looking for boundaries as much as I'm looking for coordinates. Sorry for new newbie question. I'm not sure where to look to find reliable and up-to-date data.

We have a table in our database that has latitude and longitude geocode coordinates paired with US zip codes. A sample of the data looks like this:

Zip   State  Latitude    Longitude
30000   GA  33.906553   -84.206311
30001   GA  33.810659   -84.607964
30002   GA  33.77429    -84.260712
30003   GA  33.906553   -84.206311
30004   GA  34.113832   -84.294578
30005   GA  34.079927   -84.221166
30006   GA  33.906553   -84.206311
30007   GA  33.968777   -84.43282
30008   GA  33.902022   -84.580318
30009   GA  33.906553   -84.206311

The problem is that our data hasn't been updated for a few years. Where can I obtain (for free or for purchase) updated data for this table?

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10 Answers

up vote 17 down vote accepted

ZIP codes are a habitually abused geography. It's understandable that people want to use them because they are so visible and well-known but they aren't well suited to any use outside the USPS. ZIP codes aren't associated with polygons, they are associated with carrier routes and the USPS doesn't like to share those. Some ZIP codes are points e.g. a ZIP code may be associated with a post office, a university or a large corporate complex. They are used to deliver mail.

The Census Bureau creates ZIP Code Tabulation Areas (ZCTA) based on their address database. If it's appropriate to your work you could try taking the centroid of the ZCTAs. Geography from the 2010 Census is gradually being released and the remaining states should be out by the end of January 2011.

See also: ZIP Code Geography and Mapping

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Thanks for your well-explained answer. It's clear that ZIP codes are abused, but that's what the business is using so I don't have much choice for this particular application, unfortunately. I'll pay attention to the census data for future updates. –  Ben McCormack Jan 13 '11 at 18:16
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ZCTA for 2010 TIGER are now available ftp2.census.gov/geo/tiger/TIGER2010/ZCTA5/2010 –  Sean May 18 '11 at 15:29
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@Sean, but even the Census says the ZCTA don't match the USPS true boundary, it is just the tabulation block they use. Yes, it is the most recent free source, but you need to take that caveat into consideration. –  D.E.Wright Aug 3 '11 at 1:00
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@D.E.Wright, yes, that's why they're called ZIP Code Tabulation Areas. There is no USPS true boundary. –  Sean Aug 3 '11 at 14:41
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http://www.census.gov/tiger/tms/gazetteer/zips.txt

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That looks exactly like what I would need, but the data is 10 years old. I suppose I may have to wait until the 2010 Census data is processed. –  Ben McCormack Jan 13 '11 at 17:35
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this is only 8 years old :( www2.census.gov/cgi-bin/shapefiles/national-files –  Brad Nesom Jan 13 '11 at 17:42
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You can get that exact data format for download for $20 bucks at http://www.zipcode-city-county-state-boundaries.com/

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Try the CivicSpace US ZIP Code Database. It's also available as a package in R, if you happen to use R.

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Current data from the USPS can be had for a relatively low price, between $100 and $200. There are a number of vendors that are non-exclusive licensees of USPS data. A list is available here, http://ribbs.usps.gov/files/dpv/CERTIFIED_LICENSEES.TXT. DPV, Delivery Point Validation, certifies an address as deliverable, versus an address which falls within a deliverable street and address range. 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. Two products come to mind, ZP4 from Semaphore and ZIP*Data from Melissa Data. I think that the TIGER data from 2000 will be lacking, particularily for any new ZIP codes since then. All of the 2010 TIGER should be available by April. They are rolling states out weekly.

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2010 Tiger shapefile release schedule and downloads: census.gov/geo/www/tiger/tgrshp2010/tgrshp2010.html –  RyanDalton Jan 13 '11 at 22:02
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The USPS offers this service...they should be the authority. (Although even their data seems to be compiled from a variety of sources, including but not limited to US Census...)

http://www.unitedstateszipcodes.org/zip-code-database/

They just provide a latlong (presumably a centroid) but one could always (ab)use the google Earth API to at least get a bounding box for each,

e.g.

http://maps.google.com/maps/geo?q=13357&output=xml

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The unitedstateszipcodes.org data set is third-party, not affiliated with the USPS in any way. That's why "their data" comes from multiple sources. –  Matt Ball 5 hours ago
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One thing not mentioned, but very important, is that the Census data is not a complete list of all ZIP Codes (ZCTAs). It is a list of ZCTAs that have a population, so PO Boxes, etc. are not in the data. There are about 42,000 ZIP Codes and about 33,000 ZCTAs.

For a complete file and true accuracy, you'll want to get a commercial product such as what Puddleglum mentioned.

One last thing not mentioned: all coordinates are not created equal! We've seen some very popular databases off by over 20 miles in the congested Northeast! Ask vendors to give you a sample of data in your area (not their standard demo file) and use a free product such as ArcGIS Explorer to verify (you can download a ZIP Code boundaries layer from their web server, ArcGIS Online, for free!)

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As others have mentioned, census zcta is slightly different than a ZIP Code (quickly illustrated here). Furthermore, the coordinates can be population center points (where people live) or geometric center points (mathmatical calc - often fall in forestry land, large lakes, etc). For geometric, you can get it for free here. For population-based, you'll need a commercial grade ZIP Code database like this one.

fyi - I'm a developer for greatdata.com

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If you work for a vendor and are referencing your own products, you should disclose that in your answer, as described in the community FAQ regarding self promotion. –  RyanDalton Mar 19 '13 at 14:12
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You can now get the updated 2010 data directly from the Census Bureau itself. This source has the coordinates of each ZCTA as well as some other information. It should be free/public domain.

http://www.census.gov/geo/maps-data/data/gazetteer2010.html

The ZIP Code Tabulation Area file contains data for all ZIP Code Tabulation Areas (ZCTAs) in the 50 states, the District of Columbia and Puerto Rico as of the January 1, 2010. The file is ASCII text, one line per record.

Direct link to the file: http://www.census.gov/geo/maps-data/data/docs/gazetteer/Gaz_zcta_national.zip

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The US Census Bureau has Gazetteer files:

http://www.census.gov/geo/maps-data/data/gazetteer.html

For each year, there is an accompanying webpage. Select "Zip Code Tabulation Areas", and you will see a download link for a file. For example, the 2013 file is named "2013_Gaz_zcta_national.zip", which unzips into a tab-separated file. The schema for this file contains a zip code and a latitude, longitude pair, presumably the centroid of the zip code.

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How is this answer different from: gis.stackexchange.com/a/63076/442? –  Devdatta Tengshe Nov 29 '13 at 2:36
    
That answer is relevant to 2010 only. –  stackoverflowuser2010 Dec 8 '13 at 18:29
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