The United States currently utilizes NAICS (North American Industry Classification System) as a numberial coding system to classify industries. Prior to 1987, the coding system was the SIC System (Standard Industrial Classficiation).
Trade associations, or industry trade groups, frequently offer valuable information, including industry profiles, analysis, statistics and consumer demographics, as free content. Try locating locating one of these trade associations by searching the Internet for "association" and the name of your industry or product group. Remember to consider other possible keywords. For instance, if your industry is "soft drinks," you might try using the word "beverage" to find the American Beverage Association.