Lookup sites:

Finding NAICS codes for a specific company:

Of course, often you're trying to identify the code(s) for a specific company.  In that case, use a company directory database.  Here are two that make it easy to see the codes.

This code is used by the US, but also by Canada and Mexico. Its development is a result of NAFTA, the North American Free Trade Agreement, and it allows for comparable statistics among the three NAFTA trading partners. The US Census Bureau began collecting data using NAICS in 1997, but because of the long publication cycle for the Census Bureau, NAICS did not completely replace the SIC code till 2004. The code has already been updated twice (2002 and 2007), and there are plans for more updates as well. 

The Census Bureau FAQ list is quite lengthy.  Here are the questions that I encounter most about NAICS:

• Five- and six-digit codes:  The most specific and focused NAICS codes are always five or six digits. For all three countries, codes are standardized at the five-digit level. Six-digit codes are specific to the individual countries. This allows each country to describe its economy according to its own needs.
• Two-, three- and four-digit codes:  as with the SIC codes, sometimes you'll see shorter codes used to describe broader sectors of the economy.
• Primary NAICS (or SIC) codes: A company's primary NAICS code is for the line of business that generates the most income for the company. Since large companies often have several lines of business, they also have several NAICS codes. For example, car manufacturers obviously have the NAICS code 336111 (automobile manufacturing). Because many of them also offer financing for car buyers, they also have NAICS code 522298 (All other non-depository credit intermediation). Some companies will have half a dozen or even more codes!
• Who assigns NAICS/SIC codes? ... Lots of people and organizations! 
  Each statistical agency in the government assigns the codes for its own publications, based on the answers provided by companies to surveys and questionnaires. In addition, the companies themselves choose their own NAICS codes when submitting their filings to the SEC. And commercial publishers have a variety of strategies: some use the codes they find in corporate documents (e.g. SEC filings); others assign codes themselves.
  • If you're getting odd results for a particular NAICS code search (as in, you're missing some companies you believe should be retrieved, or you're getting companies that you believe should not be there), you need to contact the data vendor to find out how they assign or collect NAICS codes.
  • Read more in the FAQ from the Census Bureau.
• Guiding principle: NAICS retains the same guiding principle as SIC:  to group together industries that have similar production processes.  See below for more notes on the implications of this.
• Updates: The code is reviewed and updated as necessary every 5 years.
• Time series data implications:  The transition to NAICS from SIC means that for some industries, time series will be broken.  Click here for a page with more detail on this question.
• Developed cooperatively by the US' Economic Classification Policy Committee (on behalf of the OMB), Statistics Canada and Mexico's INEGI (Instituto Nacional de Estadística, Geografía e Informática).

Last updated in 1987, this code is 'history', at least as far as most of the US federal government is concerned.  In 1997 the implementation of a new code, NAICS, began, and the conversion was complete in 2004. However, commercial publishers are continuing to use SIC.

Here are some important things to know about SIC:

• Four-digit codes. The most specific and focused SIC codes are always four digits. However, sometimes you'll see codes labeled SIC, but which are shorter or longer. Here's why:
  • 2-3 digit SIC codes: In order to group together data in similar focused industries, sometimes data will be presented at the truncated level of 2- or 3-digit codes.
  • 5-6 digit SIC codes: Because of the SIC code's weaknesses, some commercial publishers have augmented the base SIC codes. Dun & Bradstreet and InfoUSA are two examples of companies that have done this.
• Primary SIC/NAICS codes: Please see discussion above.
• Who assigns SIC/NAICS codes? Please see discussion above.
• Weaknesses:  SIC is weakest in the areas of the service industries and high-technology, in other words, not detailed enough.
• NEC or Not Elsewhere Classified: these are catch-all categories for industry groups that are somewhat significant, but not significant enough to warrant their own separate codes. A good example is SIC code 3469, "Metal Stampings, not elsewhere classified". Among other things, it includes such products as: ice cream dippers; stamped metal ashtrays; porcelain enameled cooking ware, store fronts, stove parts, and table tops; stamped metal floor tile; and electronic enclosures!
• Guiding principle: in the construction of the SIC code, the guiding principle was: to group together industries that have similar production processes. This means that the code reflects the viewpoint of producers rather than of consumers. (Be warned! This principle was not always consistently applied.)  Here are a couple of examples where the principle has some weird side-effects:
  • In SIC code 3751, motorcycles and bicycles are grouped together. Here you have two end products which are quite different, but grouped together in one code. This means that it is very difficult to find data on motorcycles only, or bicycles only: generally, you must go to trade associations for data.
  • In contrast, there are two SIC codes for sugar production: one for sugar made from sugar cane (2061) and one for sugar made from sugar beets (2063). In this case, you have end products which are completely interchangeable as far as the consumer is concerned, but because the production processes are very different, there are two codes. This means that in order to find data about sugar production, either you must collect data for both SIC codes, or hope that you can find data collected at the truncated three-digit level.

If you have an SIC code, but need a NAICS code (or the other way round!), use one of these concordance sites to convert from one to the other.  Both sites include other codes as well.  (For more information about other codes, click here.)