The Standard Industrial Classification (SIC) code system has been used since the 1930s. It was developed by the Interdepartmental Committee on Industrial Statistics, established by the Central Statistical Board of the United States who developed the List of Industries for manufacturing, published in 1938, and the 1939 List of Industries for non-manufacturing industries, which became the first Standard Industrial Classification for the United States. The SIC system was last revised in 1987 and while it was last used by the Census Bureau for the 1992 Economic Census, many databases still include it as part of their indexing. In some cases, particularly when it comes to retail, using SIC codes is better or more efficient than using NAICS codes.

The system is broken down into 10 Divisions (A-J) and each is then divided into Major Groups (2 digits) and then into specific 4 digit numbers. Here is a chart of the division structure:

For those doing historical research, we have also included the records for the previous editions of the SIC manuals.