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.
Lookup system to findthe SIC code for keywords that you enter (transfers you to OSHA web site).
Correspondence tables show the relation between individual 1987 SIC and 1997 NAICS codes. See also How NAICS Will Affect Data Users.
Correspondence tables showing the relation of 1987 to 1977 SIC industries [PDF] are presented as scanned images from the 1987 SIC Manual.
Definitions of individual SIC codes may be accessed through the first two links under1997 Economic Census, above.