Standard Industrial Classification (SIC) Number

Per Wikipedia

The Standard Industrial Classification (abbreviated SIC) is a United States government system for classifying industries by a four-digit code. Established in 1937, it is being supplanted by the six-digit North American Industry Classification System (NAICS code), which was released in 1997; however certain government departments and agencies, such as the U.S. Securities and Exchange Commission (SEC), still use the SIC codes.

The SIC codes can be grouped into progressively broader industry classifications: industry group, major group and division. The first 3 digits of the SIC code indicate the industry group, and the first 2 digits indicate the major group. Each division encompasses a range of SIC codes: for instance, the division of manufacturing holds all SIC codes with the first two digits between 20 and 39. To look at a particular example of the hierarchy, SIC code 2024 (ice cream and frozen desserts) belongs to industry group 202 (dairy products), which is part of major group 20 (food and kindred products), which belongs to the division of manufacturing.

Please see [1] for a listing of SIC codes.

Per Census:

The Standard Industrial Classification was replaced by the North American Industry Classification System (NAICS) starting in 1997, but several data sets are still available with SIC-based data. Both SIC and NAICS classify establishments by their primary type of activity. Reference for this citation is: [2]