MapTechnica Frequently Asked Questions

Answers to questions most common questions about MapTechnica, our products, ZIP codes vs ZCTA, and our data products.

  • Is MapTechnica's ZIP code geodata based on ZCTA or USPS ZIP Code data?

    Our data are (is?? are??... are) derived from the U.S. Census Bureau's ZCTA data which is more closely tied to true geographic boundaries than U.S. Postal Service ZIP Codes.

    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau
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  • Huh? ZIP codes don't have geographic boundaries?!?

    Strictly speaking, U.S. Postal Service ZIP Codes are not geographical, but, rather, administrative constructs. They are actually a set of routes carriers take to deliver mail rather than a predefined geographic area with fixed borders. U.S. Postal Service ZIP Codes change frequently, are abstract in nature, and can be difficult to visualize. Therefore, it is quite difficult to get "true" ZIP Code boundary data, which is why the Census Bureau came up with ZCTAs in the first place.

    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau, boundary, boundaries, geo, geographic
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  • ZIP Code, ZIP Code, or ZIP code?

    All are technically correct. The term, "ZIP Code," was originally trademarked, but that trademark expired in the late '90s (source), so the "™" symbol is not necessary (though the U.S. Postal Service still uses the full trade dress for some reason, so I guess they're holding onto their glory days).

    Here at MapTechnica, we use the capitalized 'C' (e.g. "ZIP Code,") when referring to U.S. Postal Service ZIP Codes. We use lower-case versions (e.g. "ZIP code," or "zip code") as a generic term when the distinction between the U.S. Census Bureau's ZCTAs and the U.S.Postal Service ZIP Codes is irrelevant.

    Just to be 100% clear, MapTechnica does not sell U.S. Postal Service ZIP Code boundary data. We sell/use ZIP code boundary data derived from U.S. Census Bureau ZCTAs.

    TL;DR: "ZIP Code" = USPS ZIP Code; "ZIP code" or "zip code" = generic use; ZCTA5 = U.S. Census Bureau ZIP Code Tabulation Area

    ZIP, ZIP code, ZCTA
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  • What the heck is a ZCTA then?

    I'll let Wikipedia answer that:

    ZIP Code Tabulation Areas (ZCTAs) are statistical entities developed by the United States Census Bureau for tabulating summary statistics. These were introduced with the Census 2000 and continued with the 2010 Census. This new entity was developed to overcome the difficulties in precisely defining the land area covered by each ZIP code. Defining the extent of an area is necessary in order to tabulate census data for that area.

    Source: Wikipedia.org "ZIP Code Tabulation Area"

    ZIP, ZIP code, ZCTA, Census, USCB, U.S. Census Bureau, ZIP Code Tabulation Area
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  • Why are you using ZCTAs instead of ZIP Codes?

    To paraphrase Sir Winston Churchill, ZCTAs are the worst form of geodata, except for all the others. I'm sure if he knew what geodata was, he would agree.

    Simply put, ZCTAs are the most readily available, affordable source data available for mapping applications.

    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau, affordable
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  • How similar are ZCTA boundaries to ZIP Code boundaries?

    In the vast majority of cases, they are the same (or nearly so). However, unlike ZCTAs, ZIP Codes can cross state and municipal boundaries, and are prone to frequent change. There are definitely instances where ZIP Codes are added by the USPS, as is the case with "expansion" ZIPs, to accommodate rapidly growing areas. There are also ZIP Codes that are used for commercial purposes that have no boundaries, per se, but are rather single points on a map. Furthermore, there are ranges of ZIP Codes that have identical point locations such as post office box stations.

    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau, differences, similarities, po, post office, post office box, p.o. box
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  • Are all ZIP codes [see what I did there?] included in your database?

    No. There are roughly 42,000 ZIP Codes in use by the USPS. As of the 2010 Census, there were only roughly 32,000 ZCTAs. The USCB chose not to create ZCTAs in unpopulated areas, and, as mentioned above, not all ZIP Codes encompass actual geographic areas that can be shown on a map.

    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau, quantities, counts
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  • Do your geodata products cover the whole United States?

    Short answer: yes.

    To be clear on one point: ZIP Codes do not cover the whole U.S. There are gaps in unpopulated areas like, for example, the deserts in southern California/Arizona, so it is not true to say that 100% of the U.S. is covered by ZIP codes.

    ZIP, ZIP code, ZCTA, cover, coverage, gaps, holes, land mass, landmass
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  • Do your geodata or boundary data sets include P.O. boxes or single-point ZIP Codes?

    No, the U.S. Census Bureau does not include in their ZCTA data single-point ZIP Codes like P.O. boxes and tall buildings that have their own ZIP Code. It makes sense, actually; you can't live in a P.O. box, and generally speaking, tall office buildings don't have any population data. Therefore the U.S. Census Bureau doesn't include them.

    Because our data are derived from theirs, our data sets do not include single-point ZIP Codes either.

    ZIP, ZIP code, ZCTA, po, post office, post office box, p.o. box, building
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  • How often are your data products updated?

    We update our boundary data products whenever the U.S. Census Bureau updates their TIGER/Line source data. Typically, this is done once a year in the last quarter of the year. However, there is no guarantee that this will happen since they do not have a published release schedule. Once they update their files, it typically takes us a few weeks to convert, productize, and quality test our products that rely upon the U.S. Census Bureau data.

    updates, update, frequency, up to date
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  • The USPS just split my zip code in two. When will this show up in your data?

    With the caveat that we do not use USPS ZIP codes, we use USCB ZCTAs (see all related FAQs above), see the previous FAQ. In our experience, though, expansion ZIPs do not show up in the USCB's non-census-year updates.

    USPS, post office, split, expansion, USCB
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  • Am I safe to use ZCTAs instead of ZIP Codes for my mapping application?

    Define safe.

    Life and death safe? You'll probably want to question why someone's life would be in the balanced based on the accuracy of your mapping data.

    Practical day to day use safe? Absolutely. By definition, a mapping application needs to draw boundaries in some fashion or another. It's hard to draw a boundary for something that has no boundaries by definition (e.g. a P.O. box station).

    For geolocation services such as store locators or distance calculators, it's a good practice to augment the ZCTA data with actual ZIP Codes if you can ascertain their locations. There are a variety of means, free and paid, that will help you do this ranging from Google Maps searches to Wolfram Alpha. Note that they tend to frown upon bulk searches or scraping. Both services have subscription geolocation lookup services.

    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau
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  • Where can I learn more about ZCTAs and ZIP Codes?

    Here are a few articles that will help:

    Source URL
    Wikipedia.org "ZIP Code Tabulation Area" http://en.wikipedia.org/wiki/ZCTA
    U.S. Census "ZIP Code Information" http://www.census.gov/geo/www/tiger/tigermap.html#ZIP
    U.S. Census "ZCTA FAQ" http://www.census.gov/geo/ZCTA/zctafaq.html
    ZIP, ZIP code, ZCTA, USPS, Census, USCB, U.S. Census Bureau, learn more
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  • What is a "Canadian FSA?"

    An FSA is an acronym for a "Forward Sortation Area," which is the 3-digit prefix of a Canadian Postal Code. FSAs are somewhat like U.S. ZIP Codes in that they designate a region of postal addresses and can be used to define territories or areas that are more refined than an entire province.

    Find out more in this Wikipedia article.

    FSA, Forward Sortation Area, Canada, Canadian, Canadian ZIP
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  • What is a "shapefile?"

    A shapefile, officially referred to as an ESRI Shapefile, is file format used by GIS (Geographical Information Systems) software.  The U.S. Census Bureau uses shape files to visualize various data like U.S. ZIP codes, County and State borders, congressional districts, and more. We use these shapefiles to generate the tileset overlays designed to be used with custom Google Maps applications and mashups.

    Find out more in this Wikipedia article.

    shapefile, shapefiles, esri, GIS
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  • What is "TIGER/Line"?

    According to Wikipedia, TIGER/Line is...

    Topologically Integrated Geographic Encoding and Referencing, or TIGER, or TIGER/Line is a format used by the United States Census Bureau to describe land attributes such as roads, buildings, rivers, and lakes, as well as areas such as census tracts. TIGER was developed to support and improve the Bureau’s process of taking the Decennial Census.

    The TIGER files do not contain the census demographic data, but merely the map data. GIS can be used to merge census demographics or other data sources with the TIGER files to create maps and conduct analysis. TIGER data is available without cost due to the requirement for U.S. Government publications to be released into the public domain.

    Find out more on the U.S. Census Bureau’s web site or in this Wikipedia article.

    TIGER/Line, Tiger, line, USCB, Census, U.S. Census Bureau
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  • What is a "tileset" and a "tile server"?

    A tile is simply a square graphic file (PNGs in our case) that, together, make up a tileset.  

    When you look at a Google Map, you’re actually looking at a bunch of tiles (think The Brady Bunch opening where each Brady head is a tile). Google Maps figures out the boundaries of your map against a vast set of images and serves up only the tiles needed to draw the map you’re looking at.  

    These tiles are stored and pulled from a tile server. Google has theirs, and you can easily create one for yourself to draw whatever you want over the map.

    tile, tiles, tileset, tileset, png, layer, google maps
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  • What scripting languages can be used with MapTechnica's tilesets?

    To draw a Google Map, you need to use JavaScript. (But you knew that.) This JavaScript can live on any web page written in any scripting language (or none at all if you don't use dynamic features). The tileset is inherently a set of graphic files, so any web server capable of serving images can be used to use the tileset regardless of the server-side scripting language in which it's written.

    Note that the dynamic marker overlays like ZIP code labels or county names you see on our maps tools are drawn dynamically and require a data-driven site to work. The dynamic examples provided with MapTechnica.com's tilesets are written in PHP for use on a PHP/MySQL server. Each tilesets comes with MySQL, CSV and Excel versions of the data needed to draw these markers, so they can be used for any application.

    Languages like ASP, .Net, or Java can certainly be used, but they are not supported in the example files, nor can we answer any questions regarding their use. (Sorry, but we're LAMP developers here.)

    language, script, programming, php, asp, net, java, javascript, windows, mac, os x, linux, lamp, google maps
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